Susan, et al.:

If you can ever >ever< >EV-ER< get your hands on a Sony Model TC105
four-track, variable-speed, tone-indexing recorder, do it.  They were the
original, and they'll always be the best in my unhumble opinion.  Their
modifications were two:  (1) They added tone indexing as a momentary
push-button on the front panel right between the track selector and RECORD
button, and (2) they added the variable speed capability by doing
something with either the power supply voltage to the motor or something
with the frequency of the A.C. source--either way, it added a small cage
protrusion to the back of the unit that got warm whenever you were
operating in variable-speed mode, and it made the machine such that you
could no longer store the line cord in the rear receptacle built into the
machine designed for just that purpose because that's where the extra
hardware was put.  I've had three of these machines in my life, two of
them I had together for nearly 20 years before they both died of old age
and incredible overuse (on the order of 16 hours a day, seven days a
week).  They were the best four-track recorders that there ever were, and
if you could ever find a reconditioned/rebuilt one, grab it.

Oh yes, on one of my units there was a third modification--the tape
lifters had been clipped off (you could feel the place where they were
actually bent or clipped off with some sort of small metal-cutting tool)
so that when the tape shuttled in fast forward or rewind, you could hear
the chatter and the tone indexing tone.

God
how I miss those Machines!  I used to transcribe all my flexible-disc
magazines onto 3600-foot rolls of tape running at sub-15/16 IPS so I could
get over 24 hours of reading on one roll of tape.  You could fit half a
year of one four-disc magazine on one roll of tape!  Imagine being able to
sit and listen to something for up to six hours straight without having to
flip the tape over or push a button or anything!  I loved it!  I edited
out all the "End of Side One" type messages from the discs, and you wound
up with just oodles and oodles of straight reading.  Of course, that's why
I had multiple machines--one for recording, one for reading and switching
off to
the other machine when there wasn't a lot ot record to give the reading
machine a rest.  Because I dubbed everything off the discs at 33rpm, the
recording machine was only in use one-fourth as much as the player, but it
had four times the wear and tear on it because the tape was moving at
7-1/2 IPS.  Ah, those were the days!