Re-seating the film advance crank

[John Fontana]

I have just bough a second hand Mamiya 645 1000s.
The film advance crank just fell off and despite following the manual instructions, I cannot get it to lock in place.
When I look at the plate beneath, the edge of the plate seems to have lifted upwards as arrowed in the attached picture. I believe this has been wrenched up, should not be there and is preventing the crank from sitting squarely and locking into its lugs.
Am I right and should I gently attempt to press this flat?

 

[John Fontana]

Or is this in fact a stop that should be there?

 

[John Fontana]

The camera has no film in. I switched to multi exposure and the crank does now seem to have locked. The release catch on the crank is protruding. Is this correct?

 

[dxqcanada]

Are you referring to a Service Manual ? If not, seek it out.

 

[earthmanbuck]

The camera has no film in. I switched to multi exposure and the crank does now seem to have locked. The release catch on the crank is protruding. Is this correct?

I have film in my Mamiya 645 at the moment so I can't check this out, but I seem to recall that the film advance will lock up after one turn if there is no film in there. If you take the film spool out of the back and re-insert it, it should reset and you should be able to see whether it will still turn or not.

Hope I'm understanding the issue correctly.