As long as I have it apart, I'd like to test the field coils. They are loose in their mountings, which leads me to believe something has happened inside. Are the individual conductors wrapped, or just varnished?
I don't have access to an inductance meter. In case I get use of one, how many microhenries should they test to?
If you have doubt about the field coils just change them. They are available as lot of the parts needed for a starter rebuild.
At Snyders it is T-5107 for $63.75.
they can be rewrapped, usually
I considered just replacing them, but I have these wired in series for 12v, and I don't want to go through that PITA again with new coils.
The starter worked really good, until I overworked it recently with an overly tight engine.
I do not change the starter from 6V to 12V I keep the 6V set up with a 12V battery for 11 years now .
I use the right big wiring and a starter relais without any problem till now.
Watch also following discussion.