Help !!!! I am going nuts trying to get 2 hammers from getting caught on the backchecks when doing rapid repetition. At this point I have tried just about everything and although the notes are better they still get caught if you repeat too much. I have adjusted letoff. drop, rep springs, rep lever height, backcheck height and angle as well as distance. I am going to remove the whippens , measure and repin the action centers on all of the flanges. I am also going to remove the keys and polish and lube the keypins. The knuckle cores are aligned to the jack and I have put teflon powder on the knuckles as well as new liquid graphite on the jack tops and rep levers. Perhaps the jacks are not getting far enough under the knuckle ?aybe the hammer height is not right ? According to a list of grand regulation issues I got at the recent NCRC Convention a weak rep spring can cause loss of repetition. I checked this out but the springs do not feel too weak to me. Ideas anyone ?

It's a frustrating problem. Is the jack under the knuckle when the backchecks catch, or has it slipped out? Check the repetition bridge height, and the tightness of its joint.

make sure the pinning on the repetition lever is firm. 4 grams of resistance at least. then you can regulate the rep spring, so the hammer rises evenly (not jerkily or too springy) from check. with the action at rest, press the toe of the jack so it slides out from under the knuckle, and you should see the hammer 'wink' slightly down, then up as you release the jack and it slides back under the knuckle. align the back of the jack with the back edge of the knuckle core, hold the hammer down with one hand and whack the key firmly to make sure the jack is not slipping out under a hard blow. and burnish off that graphite...
good luck. this one can be frustrating...

bcnu
david