Just wrote a blogpost about my Unisys PW/2 Series 300 machine… My parents were the original owner, and I am the second owner of this dinosaur. And if people need a manual, then I have it scanned and there is a link to it on the blogpost.
Happy reading…
Unisys PW/2 Series 300
Nice machine!
I have memories of how the Miniscribe disks chirp when they seek… 
(I upgraded my 20MB Micropolis hard disk with one of those babies!)
Thanks. Well… I am happy that I am not listening to that beast of a drive any longer. Holding on to the drive though, because of the content and because I need the parts, if I have to revert the machine to original state. 
A friend of mine had a Fijutisu 750M full height hard drive that I was pretty sure set off the seismic sensors at Cal Tech every time the head reset (which seemed fairly regularly).
Powering it up sounded like the Tasmanian Devil.
Ohhh yeah… Not to mention those old tape drives they used in datacenters.