Here it is:
It's in not-bad cosmetic condition. I gave it a good clean up, Marshall gave me a new handle as well. It smells most fragrant.
It is dickhead loud. The previous owner hasn't exactly maintained it well. It works but it could do with a service and some tubes replaced. Nothing heavy. I bought it as I'd been borrowing an earlier MkI super bass off a friend that sounds amazing, this one didn't quite sound as good so I had Marshall look it over and quote me for basically making this one sound like the older model exactly and they quoted £140 including full revalve and a courier to deliver it, so it's not a big job and if you're competent as an amp-fiddler you could do it yourself.
Not having 140 pence at the moment means I'm selling it as it is for £350. If any of you Americans like the look of it then UPS will deliver it to you for £141 making the total just under $1000 which is apparently cheap for a vintage JMP according to the investment bankers on the Gear Page.
I also have a matching, slightly later, 4x12 cab for it. It's the bass cab model, it's from 1980 and has 4 x Marshall logo Celestion black-backed speakers in it at a rating of 260watts. It sounds killer for guitar. That one is £175