The 6 volt starter has a larger-diameter armature shaft than the 12V model. I've got both examples stashed away in the shed, so I could do some measuring after it gets daylight tomorrow and let you know which one to look for. One possibility you might be encountering is some worn bushings in the starter that allow the armature to drag the pole shoes under load and bind up the starter after the armature gets hot and expands a little.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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