I am experiencing the same issue but I have replaced the Transfer Belt Cleaner since this issue began and it is still happening. Is there anything that can be done?
I found this information that should help you.
If spots or lines appear at regular intervals on the prints, measure the distance between the defects to identify the part of the printer that is causing the problem.
We have had problems with our Phaser 7100 for almost a year. In most cases, there are dark streaks on the output (s.attachment). This happens especially when the printer has already warmed up. We have exchanged all imaging units and the waste cartridge (long time ago).
t will probably be due to a consumable. Unfortunately, no support has yet been able to tell us which part could be responsible for this. I would be very grateful if someone could help us here.
Best regards, Christian