Your Itasca 40U most likely has a HWH leveling system, which has a manual dump switch for the air bags. It also dumps the air bags when you select automatic-leveling. You will find a link to HWH (and owners manual) in a sticky on the Winnebago forum.
Your MH is quite similar to D Lindy's I suspect. You do have your motorhome listed, just 2 clicks away from here, good job! And welcome to irv2.com
2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert theConstitution. "Abraham Lincoln"