I had the same issue. I pumped my brakes to keep pressures in check until it would stabilize. I will be putting in a new dryer for the tructor !
I agree having a good knowledge of the truck via the TM's, personal/professional experience and good trouble shooting skills . I went to drive the tructor yesterday got everything to stabilize headed down the road and bang, low air warning brakes come on the truck stops. I had popped an air line. I pushed in the brake override and reved the engine enough to get some air pressure and release the brakes. I was less than a 1/4 from home so I just backed up into the driveway. Took me about 20 minutes to find the line. Being able to hook up my shop air compressor to aid in finding the leak was instrumental. It popped the line for the hand brake at the valve under the cab. Hard to reach but 30 minutes later it was back together and good to go.