[Gordon]

Here is a thought for you! Your wet tank has no check valves, If your wet tank drops because engine air bags- compressor governor- regulator and red knob valve for engine belt air bags. The wet tank should be the same pressure as aux tank till 70 psi because protection valve on aux tank supply then if it is wet tank aux psi will stop or slowly drop. While driving watch aux gauge if Primary and secondary tanks are holding and aux gauge ie going from 100 psi to 120 psi every few minute’s then check wet tank. Pull up your air schematics and follow the air