I think I've come up with something that will work.
The outer and inner cross section of the roller is .7" and
.5" so I dug around at Weird Stuff to see if any old DC2000
drives were close. The Colorado 250 appears to be, and with
a bit of work with a small flat blade screwdriver I was able
to remove the rubber from the .5" shaft. Now, I need to clean
the goo out of one of the MCD-40 mechanisms and try it.
This may be a workaround for the HP's as well. If someone has
a caliper handy, I'm curious what the cross sections are for
the roller in that.