Well I doubt that your 948 is much older than ours and Stanley (that's his
name) runs just fine.  He's also configured roughly like yours.  I'd check
the HPIB addresses on all the drives and then match the address values to
the third digit on config.  Also confirm that the 2 HPIB interfaces are
cabled up to the right drives.  Also where's your DAT?  It's HPIB also.

Once you get 'em up and running... GET RID of the 7937s.  They are a
hardware failure just waiting to happen.  Setup a group of SE-SCSI drives.
MUCH better and very very cheap.

Wayne