[Richard]

Good diagnostics to take the port to the air bag loose and see what is going on.

I can’t for the life of me see how a piece of DOT tubing got into the manifold.

Some of them had a check valve where the coach air entered to raise the coach. It may have disintgrated over time.

Two other things came to mind while we were out and about.

Once, the coach would not raise. I got off the road by hotwiring the travel solenoids. The root cause was a cracked solder joint on the HWH board that fed the travel solenoids.

Second, and way more bizarre problem was that the system would go into travel or level mode, SOMETIMES. I sent the control module to HWH twice. It would come back and work for short while. I do found the root cause purely through luck. The module has five fuses at the bottom. They always tested good but while probing around with the DVM I would get voltages of 6 to 8 volts. Bottom line is the blade fuses had oxidized contact in their holders. Pulled them, deoxit, and dielectric grease. voila the wonky behavior went away never to return.