I was out working on my SS12 today, had some troubles with the wiring diagram but got it all figured out. Now this could help you if your wires are correctly colored, or if you spend some time looking at this and your tractor.
First is of the S/G properly wired up.
Here's the voltage regulator. I color coded my circles to the wire color.
A) green wire wire, green circle runs on the dash side up to the right terminal on the S/G
B) Red wire, red circle runs from the voltage reg. to the ammeter
C) Orange wire, orange circle runs from voltage reg. to light switch
D) Brown wire, brown circle run from opposite side, or underside of voltage reg. to the left terminal on the S/G
The larger cable from the ignition switch connected to mine on the left side terminal, I have also heard of peoples connecting on the right side terminal. How ever the Red positive wire from the ignition always connects to the same terminal as the brown wire.
This is looking in from the flywheel side of the engine, or clutch pedal side of the tractor. This wiring explanation will also only work if every thing is still correctly place, please refer to my pictures.
I hope this helps, I only covered the voltage reg. and S/G because it's all that I worked on and have pictures of, the rest is straight forward on the wiring diagram. If I remember correctly the wiring diagram is available in the craftsman/sears stickies sub-forum.