CARB WAS FULL OF RUST AFTER SITTING FOR 4 YEARS. CLEANED IT GOOD BUT STILL HAVING ISSUES. FOUND OUT THAT THIS CARB HAS BEEN DISCONTINUED. WHAT SHOULD I DO? CARB IS A 303777 BRIGGS AND STRAT, VANGAURD V-TWIN 16HP ON A SNAPPER REAR RIDER 42 INCH. MOTOR RUNS LIKE A DREAM WHILE SPRAYING FUEL IN CARB BUT NOT SO WELL BY CARB ALONE. IF I KIT IT EVERYTHING WILL NEED REPLACING, WAS HOPING FOR A NEW COMPLETE CARB OR GOOD USED ONE.