@ Jono:
Two things come to mind, since you say that you've tried different disks inside the drive and none worked, which eliminates possibilities of damaged/bad disks:
#1. Take a q-tip and put some alcohol on it and clean the inside of the drive, and see if you can reach the drive's head and clean it too. It could be dirty. Keep switching to a clean/new q-tip and rub it in alcohol as long as you don't see any more dirt comming out from the inside.
#2. If the drive is indeed DOA, getting a new one should not be a problem. Ebay, Amiga dealers, Amibench, Amiga.org classifieds...tons of places to look for a spare! :-)