Worn starter brushes can cause an open circuit that keeps the armature from spinning. If it happens again, have someone hold the start pedal in the engaged position while you give the rear of the starter housing a moderately firm tap with a hammer. If that makes the starter spin, it's time for a new set of brushes.
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
Love your enemies and drive 'em nuts!