Thanks for your comment, I had no idea. Out of curiosity, do you know if it's dangerous or otherwise unadvisable to try and start it before making this modification?
The O2 shouldn't need a PSU capacitor replacement yet.
If you want to give the SCSI disk a better chance, place it flat on a table and rotate rapidly, then stop. You should feel the spindle spin.
Hardware of this era is still quite reliable so I don't think you will have problems.
The fan is also a lot louder than I remember. Thanks for the tips sir, I'll try to get the screens running to see if I can find any fun data on the drive.