The last couple of hours have yielded very satisfying results ... both machines and all four disk drives are now humming along perfectly.... The problem turned out to be very simple - the drives have a head load solinoid, and it was sticking - kept the heads from contacting the media. A bit of cleaning and very light lubrication and all appears to be well. More of a problem getting the drives out than actually fixing them - I read somewhere that one of the big makers had looked at the Hyperion and decided to build their own due to "concerns regarding servicability". I would have to agree with that! I wonder if this is the issue which earned the drives the reputation as being highly unreliable.... ??? Regards, -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Vintage computing equipment collector. http://www.parse.com/~ddunfield/museum/index.html