model 37 question about non reliabuility

[smokinj38]

high guys. i have a mod 37 that does not fire every round with factory ammo. does anyone have a length tolerance for the fireing pin? also how loose or how much movement is there sopposed to be up and downward? what is the proper spaceing from cylinder to frame? any help would be great. one more thing, useing fired rounds, the pin strike is off center and varies spoting, could this just be a pin problem and the pin is not stikeing the anvil of the primer properly?
thanks