Stump Grinder Slant 6 Starter

I’ve had good luck taking those old starters apart. You can and clean everything with a scotch brite and some cleaner. Like post 4 clean the connections.
Me as well. As long as the commutator is not torn up and the brushes worn out, take it apart, make certain dust/ debri/ rust is not causing the armature to drag the field, blow it out good with air, grease up the bushings, clean up the commutator with some sandpaper and put it back together.

Good example is my old Farmall 100 (Super A) Built in the late 40's / early 50's I think it is original--and it was converted to 12, so it's a 6V starter on 12