It was necessary for me to replace the motor on my 1985-vintage
Cooper roll frame [ref. 010711 MMDigest].  I used a Grainger Cat.
No. 4Z837 for the replacement, which gave a better speed range
for the desired application (Wurlitzer-style band organ).

While the 4Z837 was physically a drop-in replacement for the original,
I don't think this will help Mr. Hildebrant.  Furthermore, there were
numerous additional changes I had to make to my own roll frame to
achieve consistent performance.

If the roll frame Mr. Hildebrant owns is otherwise a good performer,
then the replacement might not entail anything more than drilling some
new mounting holes in the frame's side plates and boring out the shaft
adapter with the drive tang to receive the larger 5/16" shaft (my roll
frame has seen so many modifications that I can't recall how it was
originally made).  Once that is done, space the gear motor out with
some aluminum or nylon spacers if necessary, until the adapter and
motor are in the correct place, tighten up the screws, and you're done.

It seems that Mr. Cooper did a major redesign of his roll frame about
the time I bought mine.  Unfortunately, many subsequent changes were
made "on the fly" with the result that, from my observations, there
were few Cooper roll frames made after that time that are identical.

I am told that Mr. Cooper's operations were purchased a few years ago
by Gordon Forcier, of Clearwater, Minnesota, whose address appears
below.  He went into the business very enthusiastically, but I don't
think that Gordy is making roll frames any more.  Nonetheless, it may
be possible to get some suggestions by contacting him.

  Gordon Forcier
  16352 Irvine Ave., N.W.
  Clearwater, MN  55320-2409

Incidentally, I still have the original Grainger 4Z838 motor pull-out,
in good condition, if anybody needs one.

Good luck.

Dave Vincent