Yes, you will need to replace the IBT.
i have also same i have check every but still it have a same problem with my machine xerox 7545 shell i need to change ibt transfer belt
Your problem is from the IBT unit (image belt transfer). It is very dirty inside. You need a tech to clean or replace it.
I'm getting faint toner adhesion and a repeating defect on the edge closest to the front of the printer. Initially I thought it was the yellow imaging unit, so I replaced that, but it didn't seem to help. I swapped the Cyan and Magenta imaging units (Magenta was due to be replaced soon anyway) but that didn't make a difference either. The repeating defects troubleshooting sheet indicated that the fuser was the problem, so I replaced that and the belt cleaner but still have the same problem. I've also cleaned the LEDs on all imaging units.