you have a vacum leak some where. the place i would start is the lines that go from the frame to the hub's on the back side. thats the cheapest thing to replace and a pretty common pont of leaks. there's also the yellow o-rings in the axle that seals the hub to the axle i think. marc and some one else can be more specific for you. i just replaced mine with super winch manual hub's. no problem's
