Voltages that are "too high" are no problem.
Too low is a big no-no. You
want something with a fairly close capacitance match, because too little
would probably increase the startup time on the motor and might cause
issues
if too far off.
There are others (David Gesswein?) who have had to
replace TU-56 motor
caps.
I have not yet had to do so (but it's been years
since I fired mine up,
since
I've only recently repaird my -8/e PSU). My
personal priority would have
to
be voltage and capacitance over physical size.
This matched my intuition, but I didn't know enough about the chemistry of
electrolytics to be sure it was OK to run them significantly below their
rated voltage. There appear to be cans available that get the capacitance
and diameter right (so would be easy to mount), but have 4x or 8x the
voltage rating. They are only a couple inches tall, but that isn't a
problem.
A caveat - these are not filter caps. They are motor
start caps (or they
might be "motor run" caps. They will be hard to find an appropriate sub
for.
I thought filter caps went for large capacitances, whereas motor start caps
tended toward high voltages. Are there other differences?
Thanks!
Vince