Ok have leveled gasket flanges and ensured the carb is clean (it was before). Removed newly installed complete carb kit and double checked all orifices are flowing especially two holes behind needle seat. Re-installed all parts and still no joy. Removed new carb kit (needle, seat etc) and install original unit and we have ignition! Only difference I can see would be the new rubber seat washer supplied with new kit. Old kit did not have this. Will follow up with a photo of each kit soon.
