I had once a VersaLink with black dispenser assy that didn't mesh properly with the dispenser motor.
Hi,
Most probably could be from cloged toner in the dispenser system.
And pay attention at the part no for the toner. There is a part for VersaLink C7000 (just printer) and another one for VersaLink C7025/7030 (MFP).
Gabi