i have a magic tilt dual axle trailer with 4 disk surge brakes. i noticed last night that the rotors weren't looking like the brake pads had contacted them in a while so i disconnected the trailer from the wire harness on my truck and backed the trailer up and the brakes do not work. the tounge of the trailer is sliding in and out of the master cylinder just fine though(it is an inline hydraulic actuator). seems pressure is not getting to my brake calipers. i find it odd that all 4 calipers do not work. it makes me think it is a pressure problem. any suggestions?