Somebody here may be able to help, but while you're waiting for a reply, I'd probably visit the local guitar shop and see if they wouldn't be willing to ask a technician to check the wiring of a cabinet they have in stock.It's pretty easy to re-wire the whole thing, connecting series/parallel. You could trace the wires easily enough. But you could also just copy the wiring of an existing cabinet. So hopefully you can find one in a local store to copy.