About the carb insulator.
The insulator is glued on to the carb body, after time the glue can crack and then the carb can move. So if you replace the insulator you have to make sure you glue it on.
The carb retainer screw must never be overtightened, it must not be locked all the way in, just a little tight. If you overtighten it you can crush the o-rings and create an air leak, it can also cause the glue to crack.
Since there is a o-ring underneath the carb in the crankcase that prevents air leaks even if the carb moves a little.
On the latest batches (06 and 07) engines we have fixed the issue, by modifying the insulator so the glue sticks better onto it.
Nano