I posted in the Rio portables section but I'm not sure any of the main guys still look in there.

Since the Carbon and all are mostly dead, is there any chance of fnding out who the manufacturer of the scroll wheel AND the part number? I've got 2 of these here with the same problem. And I hate to keep generating parts units buying from Ebay when the only thing wrong with this is the scroll wheel and it can be replaced.

I only see marked on it

JPN M(with a circle around it)

and on the front is

40 III