[Misc] KM BIZHUB C7000 color registration problem

[Aeg Print]

Hello everybody and happy holidays,
I have an issue with a C7000
the machine has 1,2 M pages, very well maintained overall and recently started having color reg. problems in Magenta and yellow.
The machine completes auto color reg. with out any problem and very small corrections in all colors (0.001 or even 0.000 )
In manual color reg. i get error 5 out of range) with magenta and yellow more than a pixel off.
I have 2 c7000 machines side by side for I swapped transfer belt units with no change at all . the problem stayed exactly the same.
Tried everything else that was obvious (cleaned the reg sensor etc.) with no change.
i am attaching a scan from a print.
the lines above the print is to make clear that the magenta misalignment changes side across the page from left to right,
if you zoom on the photo you can clearly see the magenta pixel on the letters.

Any advise will be appreciated. reg.jpg

[Honpress]

Hi Aeg Print,

I'm having the same problem with the color registration and the same error 5 on my C7000.
You already tried the manual color registration? Could also do the FD-Mag. Adjustment and the CD-Mag. Adjustment.

These steps don't work for me though. Yesterday I suddenly heard a strange noise in the machine behind the transfer belt unit. Pulled out the process unit and saw this white part was still rotating and tried to rotate the cam on the transfer belt unit. I'm almost certain it's not suppose to continuously rotating, only when the toner from the drums needs to be applied tot the transfer belt.
It creates a huge mess with toner spread everywhere, because the belt isn't working correct this way.
The beginning of the print on the paper is fine, but slowly shifts the colors.

Wondering if it's not the same you have too? It's the white round part in this photo. Don't know what it's called, can't really find it in the manual..
Something to do with the transfer pressure

keeps spinning.jpg

[Aeg Print]

no the machine is clean inside, there is no toner leak anywhere. the transfer belt is not the problem because i used another unit from another machine and i have the same problem.
any ideas?

[Honpress]

Haven't figured it out myself yet. But I believe the problem should be in the process unit. The belt itself had a specific speed, only I don't know what speed it should be. If he moves too fast or anything it won't align with the drums I guess? Or the drums don't have the right speed