Not that you need to be told this again, but no need to buy a new carb, especially if it is a genuine Dellorto.
-Clean the carb really well. Use an ultrasonic bath or carb cleaner and an air compressor to really blow out those tiny holes and passages.
Inspect the float and float needle. If there is gas in the float it is bad. The float needle has a rubberized tip, any damage or wear on the rubber or continued leak would be a sign to replace it.
-Use an air filter
-Check for air leaks around the carb, cylinder head, cylinder base, and exhaust. Any leaks will cause trouble.