Hi, I am getting back into the hobby after about a 10 year break. I have a Marder which has had very little use and was working ok when I last used it. I have renewed the fuel lines and fitted a new spark plug, used new Texaco super unleaded and new Castrol 2 stroke oil mixed 25:1 but it won’t start. There is fuel in the engine and the plug is sparking but when I turn the engine over with the pullstart it doesn’t seem to be firing. Is there anything I need to check?