Trouble with Zenza Bronica Etrs 120 film back

I've run into a problem with my Zenza Bronica Etrs film back recently, when I remove the dark slide from it and go to take a picture it locks like the slide is still in it. It has something to do with the little mechanism that the little tab of the dark slide presses on, i've tried working on it to get it back to normal but nothing has really worked. A little ball bearing came out too but im not sure if that's part of the problem and I cant find a spot for it.

Thank you for your help.

"A little ball bearing came out too but im not sure if that's part of the problem and I cant find a spot for it."

 

- It's definitely part of the problem.

I believe the BB forms the detent for the slide.

 

Cheapest option might be to look for a used back.

There's a ton of them on eBay for cheap you'll have no problem replacing it.

Im not sure Ive never seen any ball bearings in the backs. The mechanism for the dark slide (levers) may be dirty n sticking. Try a tiny dab of WD40 in that tab where the dark slide presses? It may free it up if you work it in a few times.

 

That tab engages the signal arm n counter. has it been giving problems advancing film?

In the SQ series back there is a small (maybe 0.05 inches) ball bearing that provides a detent action by engaging the small hole in the darkslide when it's in place. I assume the ET series likely uses the same.