HP Laser Jet series II; Apple LaserWriter II NT

I have one of each. These are getting up in years; the HP has slots
for the additional font cartridges. I think they are PostScript
printers. They use the HP 92295A toner cartridge.

Both have the same problem - paper jam. The paper will be pulled out
of the tray for a few inches, and then the machines stop. The city
will be having its special pickup soon, and before I stick one or both
out for that, or before I Freecycle one, is there a quick fix for
this? If it's an "everyone knows that one" as opposed to a "could be a
lot of things" problem, I don't mind attempting a repair. I have other
laser printers, so it's not mandatory that I get these running. I
don't have the service manuals for these.

Thanks in advance.