Hi all. I have this xerox 420 pro machine wich came with an U4 error. I reset it and it worked well for a couple of days. After that, the copier was moved and after aprox 5 copies, i showed U4 again. U4-1 to be exact. I'm not familiar with this type of machine so any advice would be really usefull. I suspect the thermal fuse, according to the manual. But i don't know where to find it. If that is the problem, can the fuse be ordered by itself or do i need a new fuser?