No one better to talk with than Chambers himself - give them a call, one of the family will answer and be able to help you out.
If it's breaking flints, the first thing I check is the frizzen rebound. Most the time when a lock is breaking flints, it is because the frizzen is bouncing too hard and snaps back and chips the flint each time. Spreading the spring slightly to stiffen it usually helps (and of course rehardening and tempering). Take the face of the frizzen to a beltsander to smooth out any serious gouges too. Don't let it overheat and ruin the temper.
-Eric