Seiko DS-320 Digital Sequencer (expansion for DS-202/250 polyphonic synthesizer)

I've seen a handful of the Seiko synths (that this is compatible with) sell on here lately, so I know that they're floating around. Here's your chance to upgrade with an expansion. The Seiko 202/250 (maybe more?) are quite rare on their own merit, so the expansions (the DS-320 and DS-310) are even rarer. Since these units didn't do very well commercially, they weren't produced for very long - hardly any were collected/kept.
If you find some demo's of what these are capable of, you'll definitley be itching for one - and this sequencer adds to the madness. 
The whole setup was supposed to rival the Synclavier (with varying results) but really amounts to some very interesting 80's additive synthesis. JM Jarre used this on a couple of his notable compositions (but, as is the case for just about every synthesizer) 
Since I don't have an actual 202/250 at the moment - I haven't been able to test it. I know that it was pulled from a functioning unit. I recently opened it up and cleaned the contacts/checked the circuit - everything seemed to be in order and I found nothing that would hinder operation. All of the buttons press and rebound properly, all of the connections are snug, and all of the screws are intact. That being said, keep in mind that it has not been tested with the unit itself and I can't offer any guarantees.
The AA battery terminals on the back-panel are clean (I believe that they're meant to power the display)
It connects to the main unit via a 20-pin ribbon cable (with a terminated header to prevent a reversed connection) - the cable itself appears to have no damage whatsoever. 
There's some minor discoloration here and there, a couple spots/scuffs but generally - it's in excellent condition. 
Digital Memory Cassette input appears to be in good shape, door pushes open and closes and the connections are all in place. 
One minor scuff on the display (as pictured) but it's mostly free of any scratches/damage. 
I know the manual is out there, but you might have to hunt for it. If you already own one of these Seiko synths, there's not much that I need to say.
Please consult my photos for closer details and a better sense of condition.