Bridgeport SeriesII air assisted knee

I have a Bridgeport Series II milling machine with an air assisted knee.
When air pressure is applied to the base of the knee it leaks very
rapidly. My question is what is in the base casting and how does the air
assist system work? I am currently using the mill without it as it hasn't
worked since I purchased it. Will feed rates be higher with the air?
Thanks
Sean
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today! For your FREE software, visit:
http://dl.www.juno.com/get/web/.