K-Frame Cylinder Not Indexing on 1 Chamber

[Gregor]

A friend just dropped off a S&W Model 13-2 .357 Magnum that is pinned and recessed.

The cylinder will turn/index and lock on all chambers, both in single action and double action. However, in one cylinder, it locks but does not rotate to the next chamber. If you put some sideways pressure on the cylinder while cocking the action, it "catches" and advances to the next chamber.

Is one of the ratchets on the extractor star causing this, or is the hand the problem?

The local S&W pistolsmith, Bob M., is no longer doing work, so I thought that I could ask for some advice on the best course of action.

Regards,
Gregor

 

[500 Magnum Nut]

If it's always the same chamber then yes, the problem is with the extractor.
How is the end shake? If it has a lot of end shake the skipping chamber might go away on it's own.