Mamiya 645 Super fires when shutter cocked

A question for any other M645 owners.

My high milage M645 Super body has developed a strange fault. When the shutter is wound it fires immediately the shutter is fully cocked.

It does this with a loaded back or 'dry fired' in Multi mode. Shutter curtains and mirror behave exactly as they should.

The effect can be duplicated on another M645 body by holding the shutter button in while cranking. My guess is that the shutter solenoid is stuck open/closed by dirt or something.

Before I take a screwdriver to it I was just wondering if anyone else has seen anything similar?

Sound like a reasonable conclusion; sticky linkage keeping the shutter release linkage engaged. I've never had my M645 do this, but I have had other cameras do the exact same thing and... it was sticky lube.

If you don't have a service manual, look here: https://learncamerarepair.com/product.php?product=43

If you already have them; pardon the interruption...

Kino said:

Sound like a reasonable conclusion; sticky linkage keeping the shutter release linkage engaged. I've never had my M645 do this, but I have had other cameras do the exact same thing and... it was sticky lube.

If you don't have a service manual, look here: https://learncamerarepair.com/product.php?product=43

If you already have them; pardon the interruption...

Click to expand...

Kino, thanks for that - nice to have a sanity check before I poke around under the hood of the machine. It's the later model of the Super, but I'm given to understand that the mechanism is largely similar.