The mower is running well now. I cleaned the carb and suspect when I altered the solenoid earlier maybe I somehow caused the floats to bind upon reassembly. I still seem to feel some air current near the dipstick tube but the tests for a blown head gasket definitely come up negative. I eventually want to get the solenoid working. I read in a repair manual I found online that you should not leave a multimeter probe in the solenoid plug too long because you could damage the circuit. I'm no wizard with a multi-meter and the owner's manual made no mention of this. I guess my next move may be to remove the shroud so I can get a better look at the wiring and see if I see anything obviously chafed or otherwise damaged. It's not real easy to find a wiring diagram for this engine and the one in the repair manual is hard for me (a non-electrician) to figure out. It seems the wire to the solenoid is a red one straight from the pt of origin in the diagram.Pull the breather off at the air filter end
Problem goes away = blown head gasket
The second check is to run the engine then turn it off and immediately it stops spinning pull the dip stick
Wafts of grey/white smoke = blown head gasket .