To oppose the rheostats, and fabricate a crappy potentiometer with the original ergonomonics, I could thread the stud of the opposing rheostat into the little black Bakelite pressure block I discovered today that accepts the fork from the knee lever. It's threaded right through and when the standard rheostat is adjusted normally, has threads available to accept the stud from the other one.
The boxes would have to be shortened just the right amount so the opposing rheostat would mount right. There's room there for the two boxes and the controller. The other knee control study would have to go. The opposing rheostat's return spring could be left off, I think. A nylon thumb screw would retain the setting where the pressure of the return spring used to provide friction to retain the setting.
The whole thing would be backward compatible with the original wiring.
I have to disassemble the rheostat again and see if a screwdriver will go into the rheostat from the far side to turn that stud into the pressure block. It may be welded to a brace. It doesn't turn when you turn the adjustment nut. So I guess I could turn the whole rheostat to get it in there.
Work didn't turn out well today. Nobody home. Six hours out of the house. Nice day, long train and bus rides. I'll meet with my DRS counsellor soon.
Doug