i wouldnt put compressed air into the carby ,cos it might damage the needle and seat of the fuel bowl arm

ide do all of the above and pull the top of the carby and check the needle and seat for a block by (blowing with your mouth) blowing through the fuel inlet pipe on the carby and if the air wont pass through then its blocked in the carby

hope this helps ,kinda mixed messages ,but all of the above should be helpful somehow