Hi Curl - Check to ensure when at 1/2 cock, the leading edge of the flint isn't pushing the frizzen(hammer) back off the pan. This is a common problem with long flints.
; If this is the case, you can use a small knapping hammer to knock off some chips off the rear of the flint to shorten it a bit. I have to do that, sometimes.
; If frizzen(hammer) to pan fit is the problem, you need to make it fit by dressing the pan, or frizzen base. If the pan is flat to the rest of the lock, then the frizzen base has to be dressed. The frizzen and featehr spring must be removed to do this, then ressembld to chekc fit, now and then as it progresses. Use inletting ink to show the highs pots, don't trust your eyes. It's not a big job, just finicky. You could send me the lock to repair, but I'd ask for assistance on ALR site. There must be someone living closer to you who could help if you don't want to tackle this job. I'm in BC. Mail me.

Daryl