Ok, so I've come up with a plausible explanation for my TK50 problem.
Apparently the drive thinks there is a tape cartridge in it, even though
there isn't one. It runs the classic "loading sequence" (slow uptake then
fast uptake) even though there isn't a cartridge present. That suggests
that it is mistaken about the presence of a tape. So, does anyone know what
all of the methods are the TK50 uses to sense the presence of a tape?
I'd like to get this one fixed as it is an E4 (I've got two B2's, one E3,
and working E4 and one dead E4)
--Chuck