Roypod
Can't remember what I said in the message that obviously went off into cyberspace, but there is some harm that can come from running the choke half on; namely if you have it on too much you will wash the oil off the bore and dilute the oil.
From there, the oil thins out as well as acidifies which pits the bearings long term... but anyway.
Effectively, you undo the carby 2 bolts, plus another one down the side of the tank. The tank and carby come off as one unit.
Then you take the side panel off, put in a new diaphragm, and take the carby off the tank and clean the bowl.
First step, get the tank and carby off
Regards