OK here goes again :-)
If you get an Escom a1200 you will see that the FDD is not connected straight to the mobo. There is a small adaptor on the line, its shaped in a right angle and it allows the escom (panasonic) PC drive to connect to the amiga. The drive is also internally hacked, so no other PC drive will work.
This is the adaptor :

Anyway. If you remove the panasonic FDD and the adaptor, bingo! A standard amiga FDD now plugs into the motherboard. Or at least it worked when i connected my a500's Chinon drive to it.
Kev :-)