Hilarious!
Had the same thing happen once, trying to get a faultering fire engine to run. Buddy had pulled the rotor in the trouble-shooting process. After a half-hour of messing around and turning it over, he reached into his pocket, pulled out the rotor with a sheepish grin, and said,
"I wonder if putting this back in would help?"
Gotta laugh, or you may start cryin'!
-Michael