Laserjet fuser rollers - cleaning

Came home with a dumpster-find Laserjet 4 (with jetdirect board) yesterday. Self-tests OK but prints with some minor repetitive ghosting on the pages (it has almost a million pages on the clock). There's some baked-on toner on the fuser roller which might[1] (most probably!?) be the culprit, but gentle cleaning doesn't seem to get rid of it; question is, how aggressive can I be with it? I don't know if the blue-gray color is just a thin coating of something magical, or if it's a hunk of solid metal which can be scrubbed. [1] it was pretty filthy inside, but I stripped everything down around the fuser and toner areas and cleaned everything there. I've not flipped the thing over to check underneath yet, but I'd expect dirty rollers to cause feed problems if anything, not image problems. As it stands it's perfectly fine for home use doing stuff such as printing out things from bitsavers, so I don't want to make it worse - but OTOH it'd be useful as a general-purpose printer if the image problems were fixable without pouring a bunch of cash into it. cheers Jules