Replacing the cord on a B&D 9542 Type 1 impact wrench. Wires pulled out from switch, now I don't remember which push in slots the brushes, field winding and reverse wire attach to.

Sometimes it can be only dirty carbonbrush holders pos 146 open it and try be carefull to pull gently and patience the brushes out pos 148 control them if one or both are hanging inside the holder try to blow dirt out and sometimes a little spray wd 40 or better a canister lighter gas push the valve on the little corner of the brush holder it will work to clean it so that after 1 minute try again to pull it out most change the brush will become free to pull out but be carefull if not try to pull on the litz wire and push on the endof the brush tapping it gently that there will come slowly movement in the brush some wood or epoxy dust can give unforeseen problems with the motor the brass litzwire inside the spring will break out the brush if you pull to hard. if its hanging and will pull in a fast way.

But If both brushes are smooth on both sides replace it and try again next there is to made a measurement on the powercable necessary to the wallconnector it has perhaps a broken Braun or Blue wire. to the switch .

But is there AC ~ on both connectors to the switch about 120V in your Country it must be on the switch and from the switch there goes one of the wires over the circuit breaker BEWARE it could be the circuit breaker self thats damaged after a few breakprotections remove powerplug from wallcontact you have to measure on a beep or a light setting by multimeter in ohm measurement thats intact and have to be active shorted by measuring on both terminals of the circuit breaker if its have passage. then its ok.

If all of the parts are measured good then measure the same way on the main switch by switch on it must be give also a beep and if that is also ok then the cable from switch to the motor must be measured from begin until end at every colored wire to the electric field if all other parts are measured it could be 1 wire in the cable between field coil and switch , but if there is also no defect to find one for the last could be the stator field ( electric field ) itself one of the 2 coils broken ? or only a connector to slide connectors also to control every where must be in good order next on every coil there are 2 wires they must give a beep on both wires of each coil there are 2 coils on the field in this case there isonly one serial connection in the field so only a measure between the 2 wires of the field must give an ohm measure result also by beeping setting the multimeter . and last and least if that is fine then it must be a faultering in the powercable hidden defect sometimes repeat the measurement again or replace it to be safe becaus efaultering can it be give only on strange turnings or positions , and next step do a measure over both contacts of the carbon brushes by push both brushes with measure contacts on the brushes both ends and turn slowly the armature by hand you should find a broken collector on the armature if not there must be a bad bearing and by excessive motion the on the commutator-side it must have ruined the ends of the carbonbrush holders they can have become have a little burr on the ends of the brushholders oronly one by a melting holder in the house the commutator- collectors of the armature can also have problems by the accident it so that (one of)the brushes come not far enoug out of the holders.to push enough on the contacts.

There must something to find in this circuit.

One can expect a small amount of arcing from a carbon brush. If one brush is arcing more than another, or if the arcing is following around the diameter of the commutator toward the other brush, the brushes need to be replaced and commutator cleaned with a commutator stone.

It could be something as simple as the brushes

Turn the brush ring anti clockwise so the top brush is to the right as you look at it. lift the spring out the way and hook it to the side of the brush holder. you can then remove and replace the top brush easily.
For the bottom brush remove the switch from the machine by undoing the cable clamp and pulling the two push on wires to the field just above the switch in the housing. Then turn the brush ring so that the lower brush holder is in the middle and remove the brush as you did with the top one. After turn the ring to one side and refit the switch. Job done. (Don't forget to release the springs back onto the brushes.)

A good place to start with Dewalt tools is the switch. Take the front off the handle and pull the switch out far enough to test the posts on the back. Plug the cord in and check for voltage where the cord attaches to the switch. No voltage, bad cord, replace the cord. If you have voltage, the cord is good. With some help, hold the switch on and check for current on the motor side of the switch. If no voltage, replace the switch. If there is voltage there, you are going to have to check the brushes, armature and/or field for continuity or shorts.

wouldnt be surprized if its pressed together as if theres plenty of oil in there,they dont normally need stripping right down

check the specs and make sure your not pushing it harder than it was built for.
replace the brushes

Remove the motor brushes and check to see if it is worn. Check for voltage on the brush holder tube. If you have no voltages trace the wires from the electric source and switch. If you have voltage it is your brushes or armature coils. You can purchase parts from the below link.

http://www.ereplacementparts.com/milwaukee-907520-ser-239a-impact-wrench-parts-c-131_5120_5406.html

i have the same impact an replaced trigger switch. i think it was 38,00, had the same thing happen with my de walt xp hammer drill.U can check switch continuity before replacing

black wire on left green to base ground white to left side. on the cord end gree on round peg black on large sdade and white on small spade, but since it's a ac it wont matter with the black and white wire.