HELP! Unix-pc disk problem

[Bob Haar CS50]

I have run into a problem with the hard disk on my UNIX-PC and would
appreciate any advise on identifying and fixing the problem.

My system is an AT&T 7300 with 1Meg RAM and an EIA/RAM COMBO board 
running UNIX 3.51 . I had the machine down for a couple of weeks while
I was on vacation - ran shutdown, booted the diagnostic floppy, parked 
the hard disk, powered down, and unplugged everything. WHen I got back, 
the system wouldn't boot up.

I have previously had occasional problems with the hard disk after a 
powerdown similar to those reported by a number of people on this 
newsgroup. The disk (a 20 Meg half-height Miniscribe) would seem 
to "stick" on power up. I would open the case and jog the head
drive motor by hand and then it would work. 

This time started the same. The machine wouldn't boot - just put up
a series of blocks on the screen. When I put it back together and
powered up, I found more serious problems. It started to boot, said it
was searching the hard disk, and then reported a disk read error. I booted
the diagnostic floppy and ran the hard disk test. On the "Read all the disk"
subtest, it reported about fifty bad blocks in three clusters.      

SInce I was planning to upgrade to a bigger/faster disk anyway, I didn't 
pursue this any further. I ordered a Seagate 251-1 40 Meg as a replacement.
WHen it arrived, I installed it, but the initialization failed with the
message "Error during disk format: Response = 4" .

My basic question at this point is whether I got a bad disk drive or is 
there something else wrong with my system or am I doing something wrong?
Are there any more tests that I can make to isolate the problem?

Additional info: I ran all the other diagnostics successfully - CPU,
memory, etc.  Also, I had gotten one of the WD2010 disk controller chips
from the group buy (thanks Thad and friends) and tried that in the
system with the "new" diagnostic floppy. Nothing changed.

If you can suggest a next step, please mail a response to me.

thanks,

	Bob Haar

	phone: (313) 986-1412 (work)
		     651-4183 (home)

	UUCP: edsews!rphroy!rcsuna!rhaar
	CSNET: HAAR at GMR.COM