Tested both cylinders with spark testor. Have good spark on bottom cylinder. Exchanged plug wires, same results. Exchanged wires from power pack & problem moved to other cylinder. Changed power pack wires back & problem moved back to original cylinder. Regulator/rectifier seems to be okay. Not sure how to test stator(s). I figure if I changed power pack wires to coil (which I did) & the problem moved to other cylinder (plug wire), (which it did), then the coil must be okay. Right now it seems to be the power pack or stator(s). But, I'm not that good with small engines so any help/suggestions would be greatly appreciated. Thanks.