I need to replace pointed chisel plus flat.and how much are they.thank you.

Either one, it will need to use plus size bits, not standard.
https://www.manualslib.com/manual/1266494/Hilti-Te15-C.html

flat chisels and other tools will be available from a good tool shop
the spring will be from the manufacturer or a service dealer for that unit

Remove the covers on the steering column. You should see 2 bolts that appear to have been broken that hold the ignition cylinder to the steering shaft. Chisel these two bolts out by tapping counter clockwise with a hammer and cold chisel or good flat tipped screwdriver. These are breakaway bolts that are used to deter theft, but are not necessary for installation of the new cylinder.

The gears inside that engage the chisel points to move back and forth are either not alligned properly or are stripped. You'll have to open up the hammer to see what, exactly, is the problem.

SDS Plus is a common connection end. Several companies make them. I have not heard of a carbide tipped pointed chisel. only a carbide tipped chisel blade and bushing tool. Hilti makes very good chisels that will fit the Bosch. Hilti's number is 1800-879-8000

The SDS designation relates more to the type of chuck on the tool for the bits than to the tool/drill itself. There are both chisels and drill bits with SDS-Plus and SDS-Max shanks, SDS-Max being the the larger of the two. As far as the tools go: Demolition hammers will only hammer and can only use pointed chisels, scaling chisels, scrapers, etc, not anything like a drill bit that requires spinning to work. Rotary hammers can hammer and rotate the bits. Rotary hammers have a selector switch with two or three positions; one for hammer only for the above demolition bits, one for rotary hammer for use with carbite tipped drill bits, and some have a position for rotation only. The rotary hammer is a more versitile tool but more expensive because of extra workings inside.

The 11316 Demolition Hammer is made to hammer only, it does not rotate the bit. It is for demolition with pointed bits or flat and scraping chisels. If you want to drill holes in cement you need a rotary hammer drill.

I have just dismantled my own TE 905 to see why it was dropping the chisels and have found the following:-

1. The chisel is worn and has almost become too small for the chuck. (mesure the thickness of the chisel at both ends of the hexagonal shaft and see the difference)

2. The chuck is worn and will probably need to be replaced.
I phoned Hilti today and was quoted £100 for ONE PART OF THE CHUCK!!!

a. The chuck as a whole can easily be removed by undoing the four torx screws that hold the chuck on to the main body.

b. The chuck can be dismantled by removing the retaining ring that holds the metal outer case in place at the front of the chuck. This is very fiddly and requires some engineering skill, the use of pointed instruments could easily result in injury.

The third fix is the one I am going to use to 'patch up' my old breaker. This involves welding some small amounts of dissimilar weld onto the points of the hexagonal section at the rear of the chisel then grinding them to near enough the original size of the un-damaged section of the chisel.
This will very crudely stop the chisel from passing the ball bearings inside the chuck. PLEASE NOTE THAT ANY HEAT APPLIED TO THE CHISEL WILL CAUSE STRESS AND POSSIBLE FAILURE OF THE CHISEL. ANY MODIFICATIONS OF THIS NATURE COULD RESULT IN INJURY TO PERSONS WORKING AROUND YOU AND ARE NOT RECOMMENDED IF YOU ARE WORKING AT HEIGHT OR WITH PEOPLE BELOW YOU. This is a fix that should only be attempted by competent engineers for use on a DIY or small job basis. Hope this helps.

Do you mean with a load on it. or without? In other words, while the air hammer is pointed downward, if you put (example, the chisel tip) against a surface to be cut/hammered/etc., it doesn't work? Because, under normal circumstances, it won't work while pointed downward unless the chisel tip is actually against something. If it's doing that under load, though, have you checked the chisel you're using? If the shaft of the chisel is broken or marred, it may not be smoothly traveling the way it should. If it's okay, you likely have a broken piston inside.

I have three suggestions for you ...

http://www.veritastools.com/

http://www.leevalley.com/home.aspx

http://www.stanleytools.com/default.asp?TYPE=CATEGORY&CATEGORY=CHISELS

Hopefully, at one of these three places you will find the parts you need.

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