First,change the fuser to see if that fixes the problem. When replacing the fuser doesn’t fix the problem, check the main drive assembly fuser drive gear for wear. I have seen the teeth on the gear worn down to a point that the gear cannot drive the fuser and it starts bobbing up and down, creating a thumping sound and/or slight grinding noise.
This problem will also cause intermittent paper jams at, or by, the fuser. The only thing to do at this point is to replace the main drive assembly [part #40X5749].
This Lexmark troubleshooting tip courtesy of Bill Raymond, a service technician here at Market Point.