I'm sure that the fuser is fragile - I have a 4L
(same engine and
case, Centronics-only interface board, no Postscript) that was really
cheap at the Uni surplus because it had no cartridge (not even a
mostly-empty one) and no fuser assembly. Some Uni person pulled the
entire fuser unit and dumped the rest on the surplus folks. :-P
If you have the same engine/case, you have a 4P and not a 4L, eh? :oP
It's a low-priority project to get that one
working again - I can see
that one of the SMT interface ICs (74LS07?) is cracked and will have
to be replaced. Dunno what else is wrong with it, since it has no
fuser.
For the price of one in USA, I'd tell you to buy another ;o)