I received an A500 Rev 6a that i'm refurbishing, and the floppy drive is not original, but a hacked into place "repair" job. Whichever repair center did it (back in the early 90's), seems to have hacked the case up a bit to accomodate the larger eject button, and the stand-off hex screws are not the correct length, so thew whole thing tilts down slightly. I can't do anything about the fact that they've masacred the case, but is it possible to buy original (working) A500 floppy drives, and the correct size stand-off hex screws?
The drive i've got works, but is noisy, although it's the eject button that is most annoying, as it doesn't sit flush with the case when there is no disk in the drive--it's always prominent.