remove the spark plugs, spray a little carb cleaner or put a 1/2 teaspoon of fuel down each plug hole.
Replace the plugs with new ones and crank the engine.
If it fires the spark timing is OK
Then try the carb cleaned in the carb ( make sure the choke is open ) then close the choke & crank the engine
If it fires then the valves are OK so that leaves the carb solenoid.
It is 1/2" so get a cheap wrench and grind it thinner or buy a real top shelf Stahlwille that is made from better quality steel so is thinner.