Zenza Bronica frame overlapping

[Rodocarda]

I have a Zenza Bronica ETRS with two 120 backs. One of them has always overlapped frame number two and three. Now the one who was working correctly is beginning to sho the same issue. I wonder if the camera has some defect that breaks the 120 backs, or is a common issue of Zenza 120 backs?
Anyone had the same problems and in case any idea on how to fix it/avoid it?

 

[moto-uno]

I wouldn't call it a common problem , I've had as many as 4 backs for my etrs(i) and never a problem as you describe . Or any problem with them . Peter

 

[shutterfinger]

Modern films are thinner than earlier films. Fuji at 3.5 mil (0.0035 inch) and Foma/Arista at 3 mil (0.003 inch) are the thinnest, Kodak 4.5 mil the thickest are cited as the cause but its likely the backs need a CLA.
Dirty mechanical film advance does not pull film smoothly and can pull up to 2 mm less film per wind than it should while clutch advance systems wear and slip sooner than they should resulting in less film being moved across the pressure plate than should be.
The frequency of CLA will depend on time between servicings and frequency of use.

 

[Rodocarda]

I wouldn't call it a common problem , I've had as many as 4 backs for my etrs(i) and never a problem as you describe . Or any problem with them . Peter

Thanks :-(

 

[Rodocarda]

Modern films are thinner than earlier films. Fuji at 3.5 mil (0.0035 inch) and Foma/Arista at 3 mil (0.003 inch) are the thinnest, Kodak 4.5 mil the thickest are cited as the cause but its likely the backs need a CLA.
Dirty mechanical film advance does not pull film smoothly and can pull up to 2 mm less film per wind than it should while clutch advance systems wear and slip sooner than they should resulting in less film being moved across the pressure plate than should be.
The frequency of CLA will depend on time between servicings and frequency of use.

Thanks so you suggest the backs need servicing?

 

[shutterfinger]

Thanks so you suggest the backs need servicing?

Precisely.

 

[paul ron]

its time for a cleaning. the counter has a special gear that has the frame stops metered. that gear is a very thin wafer where both layers should move independantly of each other and are both spring loaded.

if you do a search here, im sure you will find an entire thread of exactly how to diy with pictures
i once did with someone with your same problem.

 

[paul ron]

i found the thread.....

https://www.photrio.com/forum/threads/bronica-etrs-film-advance-issues.154511/

 

[Rodocarda]

Oh my god is very very technical. I am not sure I can open the back and see what's wrong without destroying it :-D
However I have TWO backs not working so I guess I can try with one and see what happens