MPat, welcome to the forum. You really should have started a new thread since your asking about a different gun and a different problem, changing the subject in an existing thread is not good practice, your Trailblazer's action is very different from the 29-B and your problems are different.
Without pictures I will just be guessing about some of this. I am quite sure the failure to stop multiple rounds from feeding is becasue the cartridge stop is missing. It's a 3/16" diameter ball bearing the sits in a hole under the slide arm and is moved by a relief in the under side of the arm. The gun was probably disassembled by someone not knowing it was there and it fell out & just rolled away. This size ball bearing is a standard for bicycles and one can be had for a few cents at a bike shop (Numrich has them for a couple dollars plus shipping).
The problem of it not firing could be something major. The locking surfaces can get damaged in these from shooting Hi-Speed cartridges (which most modern cartridges are). When that happens it blocks the front of the bolt rising to full locked position which reduces the locking area and cause more damage. This also can stop the slide from going froward enough to lock the action. Just guessing, but it sounds like this might be the problem and someone did some modifications to allow the slide arm to move forward with out the bolt being in fully closed position, this would leave the firing pin low. Pictured is one where this is just starting, the extra head space in it now will allow the bolt to 'hammer' the surfaces harder and rapidly cause more damage.
I have also seen bolts with the top of the locking lugs ground down by someone thinking that is the reason the bolt did not rise high enough, that reduces the locking surfaces and makes the bolt unusable. The distorted metal hits behind the lugs.
