Interestingly enough, it looks like you can get a replacement MS300 drive with the software for $199:
https://www.ebay.com/itm/New-McIntosh-MS300-Music-Server-Media-Hard-Drive-300Gb-Software-Installed-43-/273801756149?_trksid=p2385738.m4383.l4275.c10
If you were interested in trying to repair it.
https://www.ebay.com/itm/New-McIntosh-MS300-Music-Server-Media-Hard-Drive-300Gb-Software-Installed-43-/273801756149?_trksid=p2385738.m4383.l4275.c10
If you were interested in trying to repair it.