Since it is affecting both drives, it is most likely a problem with the eject signal or with the lines that send the eject signal to the eject step-motors. The common point for those lines is at the Bourns filter on the logic board, just behind the floppy sockets. I would check for a failed Bourns filter (can be blown by plugging an incompatible external drive or cable with incorrect pinout into the floppy socket). See other recent threads here about that. If it has a Plus logic board, you will have a SWIM chip rather than the IWM chip on the 128 logic board. Worst case would be that controller chip failed.

Another possibility is failing power PSU caps. You might not be getting enough milliamps to drive the step motor. Recapping is also covered exhaustively in many threads here.

Rick