I have a Davis Twigg lock that produced a pitiful spark. So I took it to Dixon's Fair in '09, knowing Tim from RE Davis would be there. He agreed that the mainspring was too weak and installed a new one from his display lock right on the spot...no charge.
I was still not happy with the spark, so I sent the lock to Bob Roller on his advice, and he replaced the guts with his late English parts. Lock is snappier but still a pathetic spark, especially for this big lock. I tried several times to re-harden and temper the frizzen, having had a long history of personal success to this end. But without significant improvement.
So I packaged up the lock and sent it to Larry Zorne at Mold and Gun Shop....all this from North Central British Columbia....when he received the lock, he said he'd replace the frizzen ON WARRANTY!!!!! It isn't even one of his locks!
I received my old girl back the other day, and she now sparks like a cutting torch. Now I'm happy. And super impressed with the service I received from everyone who had a hand in this locks make-over.