I have had floppy drived from Mitsumi which has all its installs showing on the underside. Chinon probably made the most armoured drives and lots of jumpers on back to play with too. Panasonic drives used in later a1200 are practicaly silent so it may be clicking, just not audiable. Would have thaught floppy led would have a very slight flicker to it. If it is a mitsumi drive its internals could be grounding on the shielding which would stop drive functioning properly.