Quote Originally Posted by Les Sarile View Post
The Pentax ME Super and the Minolta XE-7 have an indicator to show if film is winding properly. Seems overkill as you can judge this by looking at the rewind knob turning as you advance the film. This feature would be most helpful in cameras that mount their flash on top of the rewind knob and prevent you from seeing it turn with film advance like the Minoltax XK or Nikons F, F2 and F3. But these cameras don't have this feature.
The Minolta X-700 has it as well.
It is not overkill as the case may be that the leader is correctly inserted into the receiving sprocket but the perforations are not correctly engaged by the teeth. When you advance the film the rewind knob will turn, and the film will advance, but not being properly aligned you undergo the risk of an imprecise focusing (film slightly away from focal plane) and of an imperfect spacing between frames.

The indicator moves when the toothed knob near the receiving sprocket turns, that is the sign that the film is properly mounted and teeth engage the perforations.