Mamiya C330 Professional F - panel blocking film exposure

[MrBiswas]

I've put several rolls through my Mamiya C330 Pro F and this latest one had a black trapezoidal blockage at the top of every frame. It appears that the flap that flips up to block the film when the UNLOCK switch is engaged while changing lenses no longer retracts all the way back and now blocks a portion of the frame. See picture and example frame. I've had the camera for about a year and haven't had any issues otherwise.

Has anyone else experienced this issue? And are there any reliable fixes for it? I can't tell what changed to prevent the panel from getting held down and out of the way of the film.

Thanks very much.

 

[MattKing]

Remove and remount the lens, making sure that the UNLOCK dial returns fully to the correct position.
Check to make sure there isn't something tangled up with the flap mechanism.
@Mamiya_Repair , @grahamp and some of the other members here with extensive Mamiya TLR experience may have more suggestions.
Sadly, Horst Wenzel passed away recently, so I can't recommend him for a local repair.

 

[MattKing]

Oh, and welcome to Photrio, from either a near neighbour - assuming your location is Vancouver, BC - or a not incredibly distant neighbour - if your location is Vancouver WA.

 

[MrBiswas]

Remove and remount the lens, making sure that the UNLOCK dial returns fully to the correct position.
Check to make sure there isn't something tangled up with the flap mechanism.
@Mamiya_Repair , @grahamp and some of the other members here with extensive Mamiya TLR experience may have more suggestions.
Sadly, Horst Wenzel passed away recently, so I can't recommend him for a local repair.

Thanks for the tips. I was switching the lenses throughout this roll before I knew anything was wrong, and every frame has the same blockage. And no matter what order I use the locking and unlocking mechanism, with adjustments to other things in between, I can't get the flap to tilt all the way back down. And I by looking at it, I can't understand what on the metal piece that attaches to the flap would have kept it down and clear of the film backing. I'm wondering if some piece fell out.

And thank you for the welcome! I am in Vancouver, BC.

 

[MattKing]

This may help.
Mine is a C330 Professional - not the later C330 Professional F though.
Flap open.

Then after a distinct "clack", flap closed:

 

[MrBiswas]

Thanks for the pictures. It appears that when I switch to UNLOCK it looks the same as yours. When it's in LOCK the panel has some spring with the metal part that attaches it to the turning mechanism. I don't understand how it would have turned further to tilt downward in LOCK.

 

[MattKing]

When in LOCK, the flap should be all the way DOWN - something is stopping that from happening.

 

[grahamp]

This is the first time I have heard of this fault, so I'm guessing a bit. I will have to pull out my cameras and investigate a bit.

Do you always wind in the bellows completely before changing lenses? There is a small projection that protrudes from the body with 'unlock' that operates the retaining wire clamp. If that is not projecting properly it may indicate a problem with the internal mechanism.

In 'unlock' the flap should be closing the film gate, and on 'lock' it drops to the base of the camera. I took a look at my C220 and C330, and the flap is connected to the pivot rod by three small screws holding a springy plate that holds the baffle. The rod has a flat ground into it. Are all three screws in place? The baffle should be in contact/close to that rod.

Operating the 'lock/unlock' control involves a little force initially, then it should release as the baffle moves to the new position.

There are some pictures of the baffle in the 220 pictures from my Mamiya TLR pages. If the baffle and mounting are in the right place, I wonder if it is the internal spring on the control that is at fault.