I replaced the caps near the speaker and my problem remains, so I tried the drive in my 6100/60 and it's doing the same

So it's the driive after all.

Plan B, has anyone put one of these in a Classic? http://www.ebay.co.uk/itm/IBM-WDS-380-80MB-50-Pin-SCSI-Drive-/380683502787?pt=UK_Computing_Other_Computing_Networking&hash=item58a28144c3