Hmmmm.... this thing is proving stubborn.

Before you put it back in the box and then kick the *ell out of it........ tempting isn't it ?

Try just putting a couple of small drops of fuel down the carb with the tank disconnected.
Give it a spin on the starter. If it doesn't start try another couple of small drops of fuel and spin it again, if it still doesn't run then give it one more try.

If it doesn't run for a short burst during this process then it is not looking good.

Someone else has posted a good way of doing this.

The only other thing I can suggest, if you haven't already done it, is to try another plug. It might be glowing when out of the cylinder but not performing correctly in the engine.

I never had this amount of trouble (fortunately) I just couldn't get the thing to start by hand when new.

If it does run by means of just priming into the venturi then it may be worth while inspecting the very thin fuel line which comes with this engine. I use normal fuel line from tank to filter and then managed to get the thin stuff onto the filter and then the carb connection. I also use `normal' fuel tube from the pressure nipple on the muffler back to the tank. That thin stuff would be easy to damage and also kinks very easily.

Reg