Ariel Proport Model 656 DSP

Does anyone have any information on where I may find a manual for this item? I know its ancient [like its owner] and Ive Googled whats left of my brain out all to no avail. ANy help is appreciated
Hi there. Like yourself, I am an old dinosaur.
I have 'inherited' one of those units and am having the same problem.
I was wondering if you had any luck or if you could toss me
any info on the 656.
Tks in advance.
Donald White