Xerox m15i copier guide broken

This sounds like the paper path guide that sends the copy by the drum modual and then to the fuser.
If the walls are stained yellow, they the "vains" plastic guides are broken and will cause paper jams. Also after the paper has been fed out of the fuser modual there are other plastic guides that might appear to be yellow in stains. these tips often break and will cause constant jams.
The door guide has to be replaces and the vertical transport may need replacing as well. You would need to get part numbers for this specific model and someone who knows how to dissasemble this machine.
End result, you may need to call Xerox for assistance.
Good luck.