ok, check your 740A drive if it set as slave or master drive. Some enclosure has strict requirements. If your Plextor drive is set as slave, then you should set your 760A as a slave drive as well. And if your 740A is set as master, make sure you do the same for the 760A. Identify what chipset does the enclosure use?? Prolific or combo of cypress and oxford 911. To find out if it is Oxford chip for firewire, hook up your 740A and click on the arrow to remove hardware, when you double click on remove hardware icon, the chipset should appear in the box. Then try to figure out a way if you can update the firmware on the external enclosure. And by the way, reinstall your firewire driver on your computer. To do that, remove the driver in your hardware profile. Restart windows, then lets windows detect the controller again, then plug in your 760A drive via firewire port.

It's an Initio INIC-1530L chipset. I tried both of my 760A drives with CS and Master jumpering, and on two different systems with different OSes (XP Pro, Vista Ultimate) with the same results.

Can someone point me to instructions on how to open a 740UF or 755UF case?

Never mind. I figured it out.

it'll be interesting to know how you get on.

i think whoever mentioned the slave vs master setting hit the nail on the head, some of these units require the drive in slave configuration, which is easily over looked