RE: carb fell off????
I use "Sensor Safe" silicone gasket maker. (Permatex)
Some say the chemical make-up will slowly eat away your motor. But the large comet and the associated mass extinction will probably occur first.
there is a little nut on the side that needs to be sealed and snugged-up (not too tight).
And make sure your throttle linkage does not over throw and loosen the carb.