I have the same problem at times with my Venus 40. It is very easy to flood when priming it which will cause the engine to be very tight if not impossible to turn. I've found I only need to seal the exaust or the carb with my finger and turn the engine over about twice to get enough fuel into the carb to start it. After its primed, it leaks a little fuel when sitting if the engine is not running, but it does not affect it after its running. The fuel you see comming from the spinner is probably fuel that spilled out of the carb before you got it started or while you had it turned upside down. Lowering the tank or mounting the engine at 90 degrees are the only ways I've heard of to solve this problem. If you mount the engine right side up, the fuel tank will be too far below the carb and will probably not draw fuel properly when you get down to about half a tank.