[BILL WILLIAMSON]

Msaby,
IF the spark shorts through the rotor, it usually leaves a rainbow looking discoloration up inside the rotor hole where it fits on the shaft. Look at it outside in the bright sunlight. Or hold the coil wire close to the steel contact on top of the rotor & crank it over. A slight THIN spark might show, but if it is a good SHARP snap, then the rotor's gone KAPOOIE! With every tune up, REPLACE the rotor, & throw the old one AWAY! They're CHEAP. (Me Too!) Bill W.