Thanks for those 2 responses.
It starts very easily. I can move the lever off choke position after about 15 to 20 seconds. It then starts to hunt almost straight away. It hunts at all speed settings but dies completely at about half throttle. Was good under load until this started happening. It still runs under load but not quite as well. The tank is clean. The spark plug is a little black but not oily.
The mower has probably only done about 8 to 10 hours in total since I bought it new.
I haven't tested the spark. I can try that on the weekend though.
