Actually a low level format on a MFM drive doesn't fix anything, it just marks all the sectors good. What you are supposed to do is input the list of bad sectors printed on the drive label and any new sectors your surface scans found bad so that the low level format will prevent their use.
Macs may be somewhat limited in drive diagnostics tools. I would try the drive in a PC, particularly with a tool like Spin-Rite and see what it says. That being said, those MiniScribes were stiction happy units. Heck my Apple 40SC finally bit the dust and that was a 5.25" Quantum drive. It never got stuck, but it finally went ker-CLUNK for the last time.
Macs may be somewhat limited in drive diagnostics tools. I would try the drive in a PC, particularly with a tool like Spin-Rite and see what it says. That being said, those MiniScribes were stiction happy units. Heck my Apple 40SC finally bit the dust and that was a 5.25" Quantum drive. It never got stuck, but it finally went ker-CLUNK for the last time.