Two way to test the stop solenoid. While touching the solenoid, turn the key to the run position. You should feel the solenoid energize and hear it click. If neither of these occur, your solenoid is either bad or good but not getting power. Before going farther, dump a small amount of fuel into the carb air horn, and try to start the unit. It the unit starts, then go back to the solenoid. If the engine starts, but then dies, it is time to test and/or repair or replace the solenoid. If you post back, please include all model numbers, so we can give you specific instructions on your unit, as our ESP is down due to the weird weather this winter.