The first G62 Walbros were HDA 48..Later models were HDA 48 C and 48 D..The first ones had a problem with transition and idle..The C and D models are identical to the 48, with the exception of a fuel nozzle inside and the length of the throttle hookup arm....If you have one of the early 48 carbs it may need the nozzle replaced with the later version..Otherwise look for a leak or stiff diaphragms...