Farmall Super C Starter Doesn't run

I have a 1954 Farmall Super C tractor I use around my farm when doing small work, like cutting firewood and running a small 6' brushhog. I have had this trouble once before several years ago and don't remember how I fixed it. The starter doesn't work or run at all and I hear no clicking or snapping or anything when I pull out the starter switch rod. When this happened before I replaced the starter switch with no improvement. The headlights work bright so the battery is not the problem. And I can crank start it up with no problem. But for some reason the armature in the starter doesn't turn. The last time I had the cover off of it and looked at the brushes they were in good condition too. Any ideas?

take starter off of tractor, put jumper cables on it, connect to a battery that you know is hot, have someone hold starter steady on floor or bench and pull the toggle. if it does not run, replace or repair.

Try having the lights on and using the starter. If the lights do not dim when the starter is (supposed to be) turning, the starter, or switch is "open". This means it is not actually getting current running through it.
The next step is to find out if the switch is failing to make contact with the starter stud under the switch. (a point of failure that is common)
To check if this is at fault, look at the switch and you will see a plunger that has a spring on it. If your tractor has a pull rod, the plunger will come in from the rear of the tractor towards the front. If it has a push rod to activate the starter, it will have the plunger come in from the front toward the rear.
Remove a terminal from the battery and keep it from touching anything.
Remove the starter switch then, if you have an ohm meter, a test of the resistance between the starter stud and ground should show Zero ohms. (NO resistance) It actually measures in the tenths of an ohm.
If it has high resistance, (no conduction, meter does nothing) the starter is open, meaning it needs to be checked by a automotive electrical shop and repaired/rebuilt. It could have a broken wire, solder joint, or copper conductor inside, or it could have a hanging brush.
If it has good continuity (conducts), the switch needs to be modified a little to make good connection with the stud on the starter. Use a chainsaw file or small rat tail file to elongate the mounting holes of the switch in the direction that allows the plunger to move farther toward the starter stud (about 1/8" will do). Then remount the switch and tighten so it is moved!. Then reconnect the battery, (put it in Neutral) and try it. Best of luck, Jim

Take the pull switch off and polish the stud on the starter and the switch and try it.

The ground for this starter is through the starter body. Try loosening the starter, lightly sanding the contact area between the starter body and the tractor's housing. That generally "fixed" ours.

Bright lights don't mean much. The lights will work just fine even with dirty battery connections.

The tractor has been sitting for a while I expect. Clean up all the connections for the heavy cables running between the battery and starter.

Check the ground cable end where it is attached at the back of the battery box to the frame. We just ran a long ground cable down to a starter mounting bolt. Not correct, but by-passes that ground at the battery box.

Are you sure the starter isnt locked up on the ring gear.

I have hand cranked it to start it several times since the starter motor initially stopped working. And I don't hear anything funny when it runs. So it must not be stuck in the ring gear. I have tested the starter switch and it was brand new two years ago when I had a similar problem. I have been working on an out-of-town job for the last several days and haven't had a chance to take the cover off the starter motor and see if the brushes are still there or if one of them is parked on a bad place on the armature contact. Maybe tomorrow I can get to it. Otherwise I guess its a new starter motor, and I am kind of short on cash since my wife is using all the money to sheetrock and insulate the living room.