Speedometer Problem (mostly) solved

I did finally get the speedometer to work. I must have hooked it back up wrong once and fried the circuit board. Two connections on the ground circuit were burnt up when I finally took the speedometer apart. After some ugly but functional soldering and more studying of the wiring diagrams, the speedo works again. I think I need to calibrate it, though, since I turned the adjustment screw when it was apart. Does anyone know how to set the adjustment? I have a multimeter and it doesn't look like something you can do while you're on the move, even with someone else driving.
I appreciate the help. The cruise control wire was what was making the wiring diagram confusing. For future reference, the 3 browns plus one brown/red (the one with the double spade connector) go to the "-" terminal. The other single-plug brown/red wire goes to terminal "31b". The red/black and red/blue go to the "+" terminal, and the white/red and the brown/black for the cruise control go to the "A" terminal.

Thanks again,

Olivier