How would I go about differentiating starter vs just the stomp switch?
Hard to do electrically with the stomp switch in place.
Turn on the headlights. Nice and bright? Now stomp the starter. Did the headlights go dim/out? If so, the battery or battery cables are likely at fault. Make sure both ends of both cables are clean and tight.
With wear, I've seen stomp switches that needed to be pushed just a bit more to make contact. Find something that you can put over the top of the switch (Shiner Bock twist off cap comes to mind) and stomp again. If that makes it crank you could either find something more permanent, check for loose stomp linkage or replace the switch.
I've never tried it, but you should be able to ...
make sure the transmission is in neutral
remove the battery cable from the start switch
remove the start switch
manually engage the starter drive (Bendix)
touch the battery cable to the stud that the starter switch contacts
If the starter cranks replace the stomp switch (or maybe just clean up the contacts).
Have the battery tested.
