My nason switch at the parking brake plunger has been intermittent.  I had a new spare switch so I swapped it out and seems to have solved the issue.  The old one isn't that old, maybe a few years. I took the old one apart on the bench and it's pretty simple.  Depending on how tight you screw down the cap, seems to be how much air pressure is needed to make the connection.   With my meter connected to the bed and black wire, I can tell when the switch does activate when I add air pressure w