Common Maxtor MFM drive failure mode -- any ideas?

[Josh Dersch]

Hi all --

I acquired a Symbolics 3640 today and it came equipped with two "large" 
capacity Maxtor MFM drives (an XT-1140 and an XT-2190).  The 1140 spins 
up fine and we were able to image it using Dave Gesswein's MFM emulator 
(yay).

The 2190 does not, and it fails in precisely the same way I've 
personally seen three or four other Maxtor drives of the same era fail:  
It spins up fine, but when it goes to load the heads, it sounds like the 
voice coil positioner for the heads is "screaming" -- it emits a 
high-pitched, quite loud whine/buzz which persists until you power the 
drive down.  The drive is unresponsive during this time.

I'm fairly sure it's not a head crash or anything like that; having gone 
through this a year or so ago with a similar drive that was scratch 
anyway, I opened it up and verified that the heads weren't stuck, and I 
see no evidence of a head crash after disassembly.

Further, the fault does not appear to be on the logic board -- we 
swapped in a board from a working 2190 tonight and afterwards the drive 
exhibited the same symptoms.

I've had this happen to other 2190s and 1140s and a few of the ESDI 
drives in the same family, some of which were working in my possession 
for weeks before failing -- has anyone else seen this? Any ideas?  I'd 
kind of like to recover the data off of the 2190 from the 3640... drat.

Thanks,
Josh