You might try seeing if you can screw the button in a bit. As I recall it's staked and threaded, backside of button on my 740 & 709 (and spare RCS assy) is flush with rod - no gap. If yours has a gap it may be coming unscrewed. OAL of my spares run 62.23 to 62.82 mm. (NOTE: I just checked the longer of the four and the button had a "gap" - skinned back spring and screwed button down) probably would be easier to adjust if in pistol and slide locked back - unloaded, of course.) If that's not the problem, haven't a clue.