> Talking to one person, they seemed to remember that these drives would 
> startup, and do a read of the bootsector.  If the bootsect was unreadable, 
> or there was a problem, the drive would spin back down (I don't claim to 
> understand the logic with this).  However don't dismiss the possibility a 
> capacitor has gone or something.

If an unreadable bootsector is really the reason for this behaviour
then reformatting the drive should cure the problem. But sometimes
the formatter refuses to format a disk if there are unreadable/defect
sectors. I once had such a RD53 which the formatter refused to format.
What helped was connecting the RD53 to an PC running DOS, where I used 
the BIOS-routines to low-level format the disk and then DOS-format to 
check if the disk is OK. The disk showed no error in this environment. 
Then I put the disk back into the uVAX and there it got formatted also 
without problems/complaints. 

I can't explain this behaviour but to me it looks like some of the 
informations RQDX3 stores on the surface of the disk were corrupted 
and thus the combination RQDX3/RD53 was in trouble. Erasing all the 
information from the disk-surface via BIOS/DOS forced the RQDX3 to 
completely reinitialize the disk ...

Ciao,
	bertram