Help locking lens onto RB67 Pro

[philcameraman]

I just picked up a 250mm lens for my RB67 Pro. Initially I was having trouble getting the lens shutter to fire, but found that it was in mirror up mode and switching it to normal allowed me to test the shutter, which seems to be working.

But here's the problem I'm having now. I can't get it to securely attach to the camera. I cock the shutter on the lens, put it on the camera, but the ring with the red dot won't budge when I try to turn it clockwise to tighten the lens onto the camera. Moving the body shutter cocks the lens and the shutter button will fire it, so the lens seems to be in place and interacting with the body mechanisms, but it isn't secure and I can just lift it up off the body.

What could be the issue here? What could be going wrong that I'm able to have the lens essentially function with the body but not be able to attach it securely? Also the ring with the red dot moves freely when the lens isn't on the body. And my 65mm lens doesn't have this issue of not being able to tighten it.

 

[Willyekerslike]

Lens cocked and body cocked?

Red dot and red triangle lined up together?

If both the above are yes then I do not know.......?

 

[philcameraman]

Yes, unfortunately I've got them both cocked, red dot and red triangle lined up. I can only move the ring a couple millimeters.

 

[Mamiya_Repair]

My experience in cases like this is that the rotating lock ring has some sort of impact damage. If it is just slightly out of round, it won't tighten on the body.

 

[philcameraman]

My experience in cases like this is that the rotating lock ring has some sort of impact damage. If it is just slightly out of round, it won't tighten on the body.

Yes I think that’s exactly it! I discovered a tiny dent on the outside of the ring. Just posted a new thread about that actually. Do you know how feasible it is to fix that?

 

[Mamiya_Repair]

Ring needs to be removed and some dents can be straightened out, other times the ring needs to be replaced.