the PSU cannot, as far as I am aware, be operated outside of the LC.

Click to expand...

Yes, you can, as far as i can remember you should find two black wires for ground (on the left) rest are + 5v / +12v / -5v 

Never tried myself, but probably a way to use a modern PSU (PC one) just for a test.

otherwise the floppy drive is missing its door.

Click to expand...

The floppy drive has no door on the LC (except if it was change for the manual inject type)

I didn't really expect to find it and I've never been a huge fan of LCs

Click to expand...

I wasn't either, but are easy to work at and useful to make floppy discs copies...

You probably can clean the board with a contact cleaner first.