Check the plug wires for corrosion in the cap and spark plug boot. My 706 sat all winter in the shed and wouldn't even fire up one spring, After looking at all the usual suspects I was coming up empty. Finally took one of the spark plug wires off and the metal connector was corroded to the dist. cap, same thing for the other five. I made new wires, bought a new dist. cap and coil she was back to work.