HP 9100B - Magnetic Card Reader drive wheel

[mstoer]

I have an HP 9100B and just managed to get the CRT running again (a transistor died in the HV supply). As a calculator it works fine now and mostly needs cleaning.

I am now trying to repair the magnetic card reader. The drive wheel had some kind of "rubber tire" on it to advance/eject the cards, however it completely disintegrated over the years into some kind of sticky goo. I am still cleaning it off the mechanical parts. I have an original service manual, but there is no mention of the replacement parts for this. I've been trying to guess what I should be putting in place of that "rubber tire". Googling for photos of one hasn't helped much so far. Does anyone have a card reader where they could give me the dimensions or perhaps have an idea what I might put there? I was thinking an o-ring or something similar might work.

Any tips would be great, thanks,
Marcell