Hi there M8

Make sure the Air Filtter is clean as a low Air flow into the engine will stop it from starting. Spent a long time trying to get mine going untill I changed the Air Filtter over for a clean one. Then it started on the secound pull

Check that flywheel turns the piston over when you turn it by hand (should be able to feel and hear it turning over).

Check for Air Leaks / fuel leaks.

Check Glow plug (new plugs can be deffective so dont just try one try at lest two).

Check one way barring as I have been told if it starts to go, it will sound like it is turnning the engine over. But it is only doing half a cycle so the engine dosnt get the compressoin it needs to start.