I don't think it even needs rotating discs or magnets.

If the solution looked better and was integrated more seamlessly with the rest of the machine I doubt there'd be the outpouring of grief, since there's so much else going on in the machine.

To take Aurich's idea further re: LEDs inserts. You could have larger, possibly ring shaped inserts, in an inanimate disc, with strips of programmable RGB LEDs. You could easily program fairly impressive mode dependent light shows - chase patterns would look potentially much better than rotating discs in representing a whirlpool.

Best of all, it wouldn't require much if any engineering time, as it'd be more of a software issue, and it'd remove any lingering doubts about mechanical reliability.