I just bought a used CVA Kentucky rifle stock that came with a Maslin percussion lock. I've checked it over and I can get either half-cock or full-cock but not both. It appears the previous owner has tried to make adjustments as some of the screws don't look like they belong to it. Without taking it all apart I can't tell if it is badly worn or poorly adjusted. Any ideas? I'll look online for the parts that match the lock I have.