How can I tell when I will need a new cork? Looking down at the cork, it has spaces all around it, spaces from the cork to the neck metal itself. There is one small square cut in the top that reveals some of the metal. Is this something that needs immediate attention? How much do Alto Saxophone Corks go for?

if you are renting the sax its free cork replacement at your local music store. however if its yours, you get it replaced for a fee.