GR-33 expression pedal malfunction-take back off?

Hi,
I just bought a used Roland GR-33 synth, and the expression pedal worked as it should for a couple of days....now it doesn't function at all, and there is what sounds like a small part rattling around in the case. Probably explains the pedal problem, right?

My question is: is there something I should know before removing the back panel? Will something fall apart that I won't be able to get back together? Anyone else have this problem?

Thanks for any help you can give me!
jfred

OK...I'll post my own reply. I unscrewed the back, and it came right off with nothing attached to it, like some units have. It's a clean looking unit in there! The nut and washer had come unscrewed from the volume pot, and just needed to be reattached and tightened.

Bottom line is: The expression pedal works just fine now.

Thanks very much for posting the followup on this in case other GR-33 owners have the same problem. I'm glad it fixed things for you.