Random thoughts:
Possible your power supply is starting to go. May need its electrolytic caps replaced. I have an A1000 that does something similar if I have too many things hooked to expansion bus.
It's also possible you need to clean the tiny switches just inside the mouth of the drive on the left. Spray 'em down with contact cleaner and actuate several times with your finger to work the cleaner in.
Old Amiga drives can be finicky with mixed media. I have an internal A1000 drive in fact, that doesn't like high density disks, even if they've been formatted as double on another system. This same drive is so picky that it doesn't even like certain original C= Kickstart or Workbench disks!
