I will speculate that on some or all chambers the cylinder is failing to "carry up," or fully rotate from one chamber to the next. This is usually blamed on a worn hand, but hands are seldom worn because wear is caused by a part rubbing against something while under pressure, and hands don't do that.
It is more likely (if someone didn't screw with the internal parts) that the pin on the hand is slightly bent so that the hand pushes against the ratchet tooth further outboard, and as a consequence doesn't rotate the cylinder as far.
Or the crane is slightly sprung so that the hand comes up against the ratchet tooth and pushes sideways as well as upward, with the same result.
And maybe it's a combination of both.
Anyway, I suggest that if Numrich has new hands (you don't want one that was fitted to a different gun) you buy one and then take it in and hand to the 'smith and tell him to go to work.
It is more likely (if someone didn't screw with the internal parts) that the pin on the hand is slightly bent so that the hand pushes against the ratchet tooth further outboard, and as a consequence doesn't rotate the cylinder as far.
Or the crane is slightly sprung so that the hand comes up against the ratchet tooth and pushes sideways as well as upward, with the same result.
And maybe it's a combination of both.
Anyway, I suggest that if Numrich has new hands (you don't want one that was fitted to a different gun) you buy one and then take it in and hand to the 'smith and tell him to go to work.