🚀 go-pugleaf

I have a Rainbow+ with the following configuration:

   896K memory
   DOS 2.11
   20 Meg Seagate ST-225 hard drive (2-1/2 years old)
   Clikclok

Lately, it has has developed a perplexing problem.  Perhaps
one of you might know what's going on.  Four months ago, the
machine would not boot up from the hard disk, after many months of
reliable service.

The hard drive made a long series of "head seek" sounds before
the terminal displayed a could-not-load-operating-system sort of message.
The Winchester diagostics said that either the controller card
or the drive itself was bad (failing in subtest 2 on the head seek
test).  Powering the system on and off didn't seem to correct
the problem.  I then ran full system diagnostics (main memory, screen,
floppies, etc.) with no errors reported.  Strangely, the system
would then boot off of the hard disk with no problems after I ran
the diagnostics.

This erratic behavior happened again a couple of days ago. This time I was
running WordPerfect 4.2, and the drive failed while saving a wp workfile. 
The Winchester diagnostics pointed to the same problem as before.  I called
Suitable Solutions to price out a new controller board. 
The representative I spoke with said that the cards usually only fail 
within the first month of service, and that my problem was probably 
in either the hard drive cable connections or the hard drive itself.  
I reconnected the hard drive cables and the system would still not boot
up.  Whle I considered my next move, I ran system diagnostics, but this
time only the individual memory and system interaction tests. 
Again, no errors reported. Incredibly, my Rainbow would then boot 
off of the hard drive.

Does anyone know what might be going on here ? 

Thanks in advance,

Bill Martin
Cornell University