So I found the service manual from some dodgy Russian web site.
Was it
this manual? If it isn't, for $3.24 you're not taking too big a risk. I haven't bought the manual myself, but I keep the bookmark handy just in case.
Try opening up the printer and taking it apart a little bit. The fuser comes out with just four screws. Pay attention to the drive axle for the fuser -- it connects with a spring-loaded coupler that slides to one side to disengage. Put it back together and see if that cleared any jam codes or anything. Alternatively for
$139 you can just replace the whole printer and keep the old one for spare parts. Probably make more sense in the long run, although if you are printing more than about 50 pages a week you might (IMHO) be better off to buy a more expensive (i.e., heavy duty) printer and be done with it. Of course now that you've invested $25--$30 in aftermarket toner, and God knows how much of your time trying to get the existing printer to work, it would be a shame to give up on it now.
tanstaafl.