Mower with BVS 143 motor fires but then stops?

Hi, the Emblem lawn mower with BVS 143 motor was working fine but suddenly stopped for no apparent reason. When attempting to restart, it fires a couple of times and dies. Petrol and oil okay, no blockages in filter, fuel line or carb. All throttle linkages are in place.
My only thought would be the engine governor, any other ideas?
Are parts till available and is it worth repairing?