Crud has found a new home between the start switch contacts.
Rap the motor with a soft face hammer several times at different locations near the back end of the motor.
With any luck the crud will seek a new resting place.
1/2 second is more than long enough to see if it will run. Extended time with the power on and NOT running will quickly fry the run windings. Hopefully your circuit breaker has prevented that.
If starting on the bench secure it down. They like to jump around when starting untethered.
Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E(SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange