Let me toss my two cents in here.
There are postings in the Tech Tips about starter motors and how-to's about working on them. It is not hard, but it can be tedious.
If you work on a starter motor, be sure to keep everything clean-- no grease and grime and NO little metal pieces, parts or shavings that can interfere with good electrical operations.
Make sure that insulation is in GOOD shape, no frayed ends, and that all connections are clean and tight --dirty and loose (even a little bit) cause higher resistance which equals voltage drop which results in higher current through the circuit.
The masher/stomper starter system is a combination of a mechanical drive and an electrical circuit.
The mechanical drive is (as has been noted) the collections of levers between your foot mashing the starter button in the cab to the starter motor housing.
The actuating lever on the starter motor housing does two things: It actuates the internal lever on the starter motor that drives the motor gear along the armature shaft into mesh with the flywheel. It also pushes the metal button down on the starting switch (that one in your picture that mounts on the top of the starter motor housing). That action makes the positive (the big red wire from the battery) electrical connection to the brushes and field wires inside the starter motor. Those magic electrical parts make the motor turn, and when the rotating armature is connected to the flywheel by the gear on the armature shaft, VOILA!, th truck engine turns over, and starts!
Nothing could be simpler. These old mechanical-shift starter motors were used on Chevrolets, GMC's, Studebakers, tractors and a variety of other engines. They are wonderfully reliable.
I strongly recommend that you keep the 6-volt electrical system for now, as any alteration to a 12-volt system will introduce a different set of variables to getting the truck up and running--not that you can do it, but the one-step-at-a-time approach is a good approach for reaching a successful result that you can depend on to be there as you make step-by-step modifications.
Get 'er goin' first. Then if you cant to go to a 12-volt electrical system you can do that later.
My '46 is 62 years old, and the 6-volt system is still in place, working fine. Why mess with success?
