[prairieschooner]

OK guys it was most likely a poor ground but here is a suggestions, these older MAC Valves are not rebuildable and they are fairly inexpensive. I was having troubles with my rear leveling so I simply replaced all of the solenoid valves, there are only 6 each for the front and 6 each for the rear;
   
they are only 30+ years old, not bad but it is time.
PS they protect the Distributor so you will need to find out who is in your area but Clarke and I found that the guys near Tom carry better stock!