A while back, I posted that I was having trouble with a percussion lock. The hole in the tumbler was stripped, and no room to cut new threads. I tried all the suggestions, and made a mess of them all. I tried fitting a similar tumbler, but the mainspring slipped off the edge of the tumbler when fired. I tried fitting a similar shape lock, but found that the lock mounting holes were not in the same location, and, when installed, the hammer was offset too far to hit the nipple.
So, I now need to find someone more familiar with locks than I am, who would be willing to make or fit a new tumbler.