So update from MikeB, obviously the wooden skewer fix isn't particularly robust, apparently it managed the first move/relocation but not the next  .   
 
Some bits he told me: 
The cable at the front panel end (which you can't really get into) is part of the membrane switches (based on other membrane switch construction he researched) so you can't replace it. 
The socket on the PCB is old school (of course) and not used any more (he hasn't found one yet), moreover, they are only good for up to 10 insertions/removals.  So don't pull it out unless you HAVE to.  Probably I accidentally pulled it out when I changed the display? it's a long time ago.  It's easy to dislodge when you change the display as the display connector cable runs under it. 
It seems trying to clean the exposed ends (very thin silver allegedly) of the ribbon cable seemed to do more harm than good.  Apparently he spent quite a while carefully exposing some clean trace x 10 with a razor blade.  Very fiddly no doubt, but he got there.   

Next step is remove the PCB socket and attempt to repair it, i.e. bend the individual contacts so they "get a grip" as it were.  He thinks they maybe can be removed individually, squeezed and re-inserted?

Hey Harley, well it would be great if you can tune it to do both, it's allot of sound(s) in a small and light box.

Y'know, the last time I was in the studio (who knows, maybe the last time I'll record), it took a good half hour to dial in our other guitarists' Line6 pedal board that he runs directly into the PA. It took 2 minutes to dial in my Peavey Classic 20mh.

20 watts of fury beats 128 patches of modeling

I saw that diagram Kim, but I don't understand it....forgive me

No worries, I see I did a piss-poor job of labeling and designating nomenclatures......by that I mean I completely missed all that altogether.  Ha!        Anyhoo, Richard and Harley explained it quite well.   

This setup worked great for that particular cab/idea I was using at that time.   

I get that diagram. There are a lot of 4x12 cabs set up with those.

Dante, by default, 1/4" jacks are shunted when nothing it plugged into them. They remain silent and no sound passes through them. That's why when you unplug your guitar from your amp, there is no amp noise.

Hey Dante, you'll get some interaction in the box with the 2 speakers in it and the additional box cubic volume should help the bass.  But hey, you'll hear if you like it.

What he said 

Richard,

  It's interesting to see if it lives up to the hype. I'm also a fan of Jeff "Skunk" Baxter, who uses one of these for session work. He claims he just takes this and his guitar and plugs into the desk with it. I can see that with an engineer working you into a mix. I'm not really convinced at this point it would work beyond a certain point as a live fly rig.

Hey Harley, very interesting journey.  BTW I'm also a big Steve Stevens fan.

Hey Dante, you'll get some interaction in the box with the 2 speakers in it and the additional box cubic volume should help the bass.  But hey, you'll hear if you like it.

Hey Dante, this is very similar to how I've wired my spare slant split stack.  If you plug in just to the top jack (non-switching), you get both speakers mono, in parallel (so impedance will halve, i.e. 2 x 8 ohm = 4ohm etc.).  In this setup, when you plug into the switching jack (I just used the simple ones (3 lugs) which connect the tip to the middle lug with no jack and open when a jack is inserted but have there own middle solder lug which you'd connect to the other speakers +ve).  So when you also put a jack in this socket, the opening of the switch bit breaks the +ve to +ve connection (green wire) that's connected with no jack is inserted and will then be stereo (2 x 8ohms (you said)).  If you just plug into the switch jack, you just get the one speaker it's primarily/directly connected to. The slight difference using a normal 3 lug switching jack to the way MJMP does it with "cliff" jacks, is they have 4 lugs open/close both +ve and -ve connections (with jack plugged in, as in diagram) where the more simple switch jack just open/closes one lug (which you use for +ve to the other speaker (green wire) and the earth is connected (the way I did it) by the metal jack plate that both jacks are mounted to and in contact with.  So the red wire in the diagram (-ve) is not needed (the way I have it) as it's connection is provided by them both being earthed/connected to the metal mounting plate (or you need to wire the 2 jacks earth lugs together if they are mounted on plastic etc.). The 4 lug cliff jack method is better, but both work.

Simple way for you though would be wire it stereo and use your cab merger when you want mono.