C3350- no colours

[tech51]

Hi all.

I have a C3350 that while producing K prints fine, has no colour reproduction.
There are no colours appearing when printing the test patterns. In addition if I do a forced stop, there is no toner on the belt.
The drums are rotating and there are no error codes. The strange thing is that after being on site for a couple of hours it did four or so colour prints but then went back to the fault condition.
I have a feeling there may be a loose connection somewhere but I would be interested to see if anyone has had something similar.
No parts have been replaced as of yet.
I look forward to your comments...

[service_man]

Hello,

First I would check the mechanic for the color units, maybe some gear is demage.
And then I will try HV Unit

[lfruean]

Try image belt unit. If not HV unit or main dev drive motor then main drive.