Have a Homelite yardvark that stopped running during regular operation. Tested and found no spark at plug when pull cord is pulled. There is an ingnition device ( coil with lead that goes to spark plug ) If i understand correctly this is the source of electricity to spark plug. Is there a way to test the "ignition device" it costs $39.00 and hate to buy one to trouble shoot by swapping parts.... any other ideas why i get no spark?