No compression. Model 760. Pump works, but chamber does not hold compression. Cannot remove the hinge pin. Can you help? Ken

https://raybuck.com/replace-chevy-gm-truck-door-hinge-pins-bushings/

Remove the door spring, old hinge pins and bushings:
1.Remove the retainer clip on the top of the top hinge pin with a screwdriver and pliers. Start to wiggle it loose with the tip of the screwdriver and then grab it and work it loose with the pliers.
2.Remove the door spring behind the hinge - between the hinge and the door itself - by locating the end of the spring and inserting the screwdriver between it and the hinge. Pry, using the door as leverage, until the spring pops out.
3.Spray penetrating oil on the top and bottom of the pins, at the bushings, to make it easier to hammer the pin out.
4.Place your long extension on the top of the pin and carefully hammer down to dislodge the pin, taking care not to hit your windshield or another part of your vehicle.
Now, it's time to grab your assistant!
5.Remove the retainer clip on the bottom of the bottom hinge pin with a screwdriver and pliers. Start to wiggle it loose with the tip of the screwdriver and then grab it and work it loose with the pliers.
6.Place your jack to hold up the end of the door to support the weight when the bottom pin comes out. Have your assistant hold the door so that it stays on the jack and doesn't fall. Pro tip: You can use a 2 x 4 piece of wood to better distribute the door's weight.
7.Spray penetrating oil on the top and bottom of the pin, at the bushings, to make it easier to hammer the pin out.
8.Carefully hammer up from the bottom to dislodge the pin, making sure your helper is holding the door firmly on the jack to support the weight. You may need to have your assistant gently wiggle the door if the pin is binding on the hinge. You can also grip the top of the pin with pliers once you start to work it loose and tap on your pliers with the hammer to fully dislodge and remove the pin. Pro tip: You can use a rag to protect the paint on your door by covering the area with it before hammering upward on the pin.
9.Use your flathead screwdriver to pry the old bushings out.
Now replace the old hinge pins and bushings and put the door back together:
10.Insert the new bushings, taking care to respect the different sizes and where they are located on each hinge. Pro tip: For the top hinge, the larger bushing goes in the bottom part of the hinge while the smaller bushing goes in the top part of the hinge. For the bottom hinge, the larger bushing goes in the top part of the hinge while the smaller bushing goes in the bottom part of the hinge. In both cases, the head of the hinge bolt goes at the larger of the two bushings.
11.Gently hammer the four bushings into place. Remember that the bushings go in the vehicle part of the hinge, not the door part.
12.With the weight of your door still on the jack, work with your assistant to align the hinges and start to slide the hinge pins into place through the bushings - bottom first, then top. Use a hammer to gently tap at first, then hammer more firmly at the end to fully engage the pins in the new bushings.
13.Place your new retainer clips over the bushings and use your small socket or a small hollow piece of tube to hammer the retainer rings in place, ensuring they are fully seated to keep the pins from coming out.
Reinstalling the door spring with or without a GM door spring tool:
14.If you have the specific GM door spring tool (spring compressor) for replacing the door springs, follow the instructions included with the tool.ORIf you DON'T have the GM spring tool, you can compress the spring in a vice and use plastic zip-ties to keep it compressed while you install it.
Pro tip: Install your three zip-ties loosely before you compress the spring and tighten them once you have the spring in the vice.
Carefully hold the spring by the side, not the ends, in case the zip-ties break. Make sure you wear eye protection as you push the compressed spring into place.Carefully cut two of the zip-ties. It can help to close the door slightly as you do this and also rotate the compressed spring to access the second zip-tie. It is difficult to cut the third zip-tie, but it will quickly break on its own as you open and close the door, popping the spring into place.

I have done a 100 of these.

The hardest part is going to be to reinstall the spring on the lower hinge arm. this is not a screw but rather a pin.
There are two hinges that hold the door to body.
when the upper and lower pins are removed the door will come away from body, it is important that before you remove the pins you take a look at the hinges.
Pay close att. to the way the hinges sit inside each other and the way the pins go in. see if they go from top to bottom or from bottom to top. also note where the copper bushings sit in hinges. each hinge has one pin and two copper bushings top go into hinge.
Over time the pins and bushings wear out ,making door hard to open and close. When the pins and bushings get so bad that the bushing is worn out and then the pins are now wearing into the hinge hole itself then this get tricky. if hinge hole is egg shaped the new bushings will not last. the door will hang again in a few weeks. this is where is get costly, the hinges now need replacing. i have gotten good at welding the holes and filing them back to shape but this takes skill or hole will be wrong and bushing will not fit or line up.

Here is a youtube video to help you.
Take note. put jack stands under door with cloth to avoid scratching door.this is to hold door when pins are removed. have somone help you, they will hold door on stands. the wires will still run through door, pull door away from body a little to allow room to work.remove the spring, it will fall out as you remove pins, remove old bushings, clean hinge area and holes,next install new bushings, apply lube to holes for pins and on bushings, slide door back on frame hinges and install pins, next slide lock washers on pins to hold pins. last is the spring. you will need a spring tool, you may rent one at auto parts store. hope this helps good day.

1. Place masking tape on the inside edges of the door, on both the inside and outside of the door. 2. Remove the door spring by using a door spring removal tool. Insert the tool into the door spring, turn the knob with a screwdriver to compress the spring, then pull out the tool. 3. Set a 5-gallon bucket under the door. This will help support the weight of the door. 4.Place a nail punch under the hinge pin, and strike it with a hammer. Repeat this until the hinge pin begins to come out of the hinge. 5.Place the end of a flat-head screwdriver under the top of the hinge pin, then strike the screwdriver with the hammer to force the hinge pin out of the hinge. 6. Place the bushing on top of the new door hinge pin, and tap it into place with the hammer. 7. Insert the new hinge pin into the hinge. Tap on the hinge pin with the hammer and nail punch to force the pin into the hinge. 8. Insert the hinge spring back into the door, and release the tension on the spring removal tool. 9. Spray the door hinge with a lubricating spray or apply grease.

I know there are a few directions but it is fairly easy to do. If you have access to an air hammer and a compressor you can use this in place of a manual hammer to make the process a bit easier.

Hope this helps.

The lower hinge on each door may have a door closing cam. It raises the door up ¼ inch when opening and this assist in closing the door. If it's wore out and doesn't work the door may not seal and the gasket can be damaged. Watch the operation of the door to see if it rises up when opened.

Leave the door shut and let the magnetic gasket hold the door in place. Put something between the bottom of the door and the floor to hold it in case it slips.
Remove the bracket holding the pin and hinge assembly taking note of order of removal of parts. Slide new cams on. You probably need two.

What pump are you speaking of.

GM Full-Size Trucks 1988-1998 Repair Information Doors - REMOVAL & INSTALLATION

R/V Series
See Figures 1, 2 and 3
If the door being removed is to be reinstalled, matchmark the hinge position.

1. If the door is to be replaced with a new one, remove the trim panels weathersheets and all molding.
   

Fig. 1: Door hinge-R/V Series

1. If the door is to be replaced with a new one, remove the glass, locks and latches.
2. If equipped with a wiring harness, remove the trim panel and disconnect the harness. Guide the wiring out of the door.
3. Support the door and remove the hinge-to-body attaching bolts. Lift the door from the truck.
4. Install the door.
5. Perform the alignment procedures indicated below.
   

Fig. 2: Door hinge components-C/K Series



Fig. 3: Removing the hinge spring


C/K Series

1. On trucks with power components in the door, disconnect the battery ground cable.
2. On trucks with power components in the door, remove the cowl side vent cover.
3. On trucks with power components in the door, disconnect the wiring going to the door, under the dash panel. Feed the wiring through the door pillar.
4. Cover the door hinge spring with a heavy towel. Using tool J-36604 or its equivalent, insert the blades of the tool between the spring coils and turn the barrel nut to compress and hold the spring. Remove the spring using the tool.
5. Remove the lower hinge pin retainer.
6. Using a plastic or rubber mallet and locking pliers, remove the lower hinge pin.
7. Install a bolt through the lower hinges to hold the door while removing the upper hinge pin.
8. Remove the upper hinge pin retainer.
9. Remove the upper hinge pin.
10. Support the door and remove the bolt from the lower hinge.
    

To install:

1. Position the door and install the bolt in the lower hinge.
2. Install the upper hinge pin. with the pointed end up.
3. Install a new upper hinge pin retainer.
4. Remove the bolt from the lower hinges.
5. Install the lower hinge pin with the pointed end down.
6. Install a new lower hinge pin retainer.
7. Using tool J-36604, install the hinge spring.
8. On trucks with power components in the door, connect the wiring going to the door, under the dash panel. Feed the wiring through the door pillar.
9. On trucks with power components in the door, install the cowl side vent cover.
10. On trucks with power components in the door, connect the battery ground cable.

ADJUSTMENTSee Figure 4 The holes for the hinges are oversized to provide for latitude in alignment. Align the door hinges first, then the striker.
C/K series utilize hinges that are welded to the door and frame. No adjustment is possible except when replacement hinges have been installed.



Fig. 4: Door adjustment check points

1. If a door is being installed, first mount the door and tighten the hinge bolts lightly.
   

If the door has not been removed, determine which hinge bolts must be loosed to effect alignment.

1. Loosen the necessary bolts just enough to allow the door to be moved with a padded prybar.
2. Move the door in small movements and check the fit after each movement.
   

Be sure that there is no binding or interference with adjacent panels.

1. Repeat this procedure until the door is properly aligned.

R/V Series:
Door edge-to-rocker panel: 6mm Door edge-to-roof panel: 5mm Door edge-to-rear pillar: 5mm Door edge-to-front pillar: 2mm
C/K Series:
Door edge-to-rocker panel: 6mm Door edge-to-roof panel: 6mm Door edge-to-rear pillar: 4mm Door edge-to-front pillar: 7mm Door front edge-to-fender: 5mm

1. Tighten all the bolts to 26 ft. lbs. (35 Nm).

Shims may be either fabricated or purchased to install behind the hinges as an aid in alignment.

Hope this help, TY for using Fixya (remember comment and rated this). Good luck.

Sounds like it has a bad o-ring. you can take it apart and replace the o ring for under a dollar. just make sure you look at how it goes back together when you take it apart they are very simple. just make sure the carefully take the right side cover off with the left side of the rifle laying on a table, everything should stay assembled this way so you can look at it. the part you are looking for is in the large chamber that the pump goes into. from the back (the side opposite the pump) remove the spring and the metal piece behind it, then use something the shove the big brass part out of the chamber and the o ring is on the big brass part . take the old o ring to a hardware store to get another one.

Take a look on amazon Amazon com Crosman Powermaster 760 pump and take a look for replacement. have a nice day

Had a similar problem ,flashing red led means door not locked, I removed door from machine removed front from door and found hinge pin for lock had come adrift, religned pin and chapped back into position .THen replaced door and door to machine .dor shut and lock worked perfectly, hope this helps