SCSI termination is all apart of the so-called SCSI voodoo. Having too little or too many terminators installed causes the entire chain to not work properly. In my experience, I've had good luck by adding a SCSI terminator cap to the end of the chain, along with making sure termination was enabled on the external device via its switch. Also, make sure the device's ID is set to 6 (if you can change it) and that it's powered on, before turning on your Mac. The Iomega v4.2 driver should work with that drive and cartridges as well.

73s de Phreakout. :rambo: