Nigel, thanks for the parts breakdown. I wondered if I am getting a good enough seal between the tank and the carb, so I ordered a new gasket first thing this morning. Only trouble is I have ordered part no 272996 & your breakdown shows 692241. They look the same but not sure on dimensions.
Reiver - the choke does fully close, but I did notice that if the screw fixing the air filter base plate to the choke lever plate is too long it stops the choke lever before the choke flap is fully closed.