>  ...removing any two sections of cable caused it to work fine

It's not bad cables, exactly, it's just the usual difficulty getting
any external chain working with single-ended SCSI.  If people would
use differential controllers and drives, they would never have this
problem.  The controllers cost more, but the drives are the same
price. Of course, only the largest are available differential, but
that's purely because people don't appreciate the difference and don't
order differential...