McCulloch 438 runs hot, now will not start?

My 2-yr-old McCulloch Mac Cat 438 began to run hot before cutting out after a few minutes sawing. Had to let her cool off before she would reluctantly restart. Spent a few hours in this frustrating performance, then gave up.

Now, after a thorough clean and service, she will not start at all. Have checked all obvious stuff e.g. fuel, plug gap, clean air filter, choke operation etc.

There is a spark and plenty of fuel getting as far as the carb (squirts strongly from disconnected carb plastic feed pipe) so I guess the probs are in the carb somewhere. Where do I start? Can I blow through with an air line? Any suggestions?