There's no hardware difference between the two. It's all in the formatting.
Suggestion: Get an ATX supply or steal the one from your PC and get your beige running. Then download the necessaries to the beige, format and copy the disk there. This will eliminate any possible PC related corruption.
If this fails, move the 475 floppy over to the beige and see if it works or doesn't there. This will determine if the 475 floppy drive is bad.
Q: When you swapped in the beige drive, did you also swap the floppy cable? Because given everything you've written above, IMHO it sounds like a failed floppy controller on the motherboard, or (fingers crossed) a bad cable.
Suggestion: Get an ATX supply or steal the one from your PC and get your beige running. Then download the necessaries to the beige, format and copy the disk there. This will eliminate any possible PC related corruption.
If this fails, move the 475 floppy over to the beige and see if it works or doesn't there. This will determine if the 475 floppy drive is bad.
Q: When you swapped in the beige drive, did you also swap the floppy cable? Because given everything you've written above, IMHO it sounds like a failed floppy controller on the motherboard, or (fingers crossed) a bad cable.