^^^ Gary's suggestion is probably the
second most common problem I've encountered.
The most common problem is light strikes due to ill-advised attempts at lightening the trigger pull, e.g. filing down the strain screw of a K frame, cutting the mainspring of a J frame.
#3 is failure of the cylinder to lock before the hammer falls in double-action, although I've examined one gun that didn't lock on one chamber in
single-action. This is tested by pulling the trigger most of the way ("staging"), then carefully listening for the "tick" of the cylinder stop engaging before the hammer drops.
FWIW I've observed this problem much more frequently on prewar revolvers, which I attribute to softer cylinder steel and the resulting accelerated stop notch wear. However, I've examined one revolver with a hammer that fell freakishly early on
every chamber, which I attribute to ill-advised garage 'smithing.
#4 and #5 are cylinder endshake and really sloppy lockup, not necessarily in that order.
Other tidbits...
Compared to larger-caliber Smiths, I've seen an unusual number of .32 Long I and J frames with bulged barrels and/or broken or bent ejector stars. I can't explain the bulged barrels. I've attributed the ejector star damage to .32ACP / .32 Auto cases getting stuck in the chambers due to the undersized rims. I wish people would use the proper ammo.
If the cylinder only advances with the muzzle pointed downwards, this indicates that the hand has been installed with the hand spring on the wrong side of the small pin- a common first-timer assembly mistake. I almost got a bargain on a gun with this problem, but decided against buying it, for fear of encountering OTHER problems caused by incompetent 'smithing.
If the gun is difficult to cock, the cylinder is hard to rotate when it's out of the frame, AND there's no discernible wobble in the cylinder or ejector rod, the cause is most likely dirt and ancient dried-up lubricant inside the cylinder yoke. This is easily fixed. However, if the gun is hard to cock BUT the cylinder rotates freely out of the frame, this could indicate that pins are bent inside the lockwork, which is NOT easily fixed. Buyer beware.