My sears lawn tractor leaks gas into the crankcase while it is not running. It has a NIKKI #697216 carburetor. I suspected the float but that seems OK. There is a shut off solenoid that works when energized but does not seem to shut the gas off. Should there be a ball or needle valve on the end of the solenoid plunger? I did not see one in the parts list. Hope I didn't loose one.

No, there is nothing on the end of the fuel solenoid. There is however, a needle and seat above the float. What is happening is there is something causing the float to not go all the way up, pushing the needle up, sealing the needle against the seat. Then fuel floods the carb and with no where else to go, the fuel floods into the engine.