There is another post in this thread that indicated his problem was much the same as ours. He opened the unit up and touched up the soldered connections where the connectors are attached to the board. If my prob returns, that is what I intend to do. My mounting bolts were a little loose and after removing the unit found only 2 of the mounting studs had shock mounts (rubber inserts around the studs). While monitoring the system found that just tweeking the unit a little bit the gauge returned to normal. The shock mounts were both on the rearward two studs. Move them so they were crossways and tightened all four down (not too tight) and the problem went away. That probably is a short term fix. We shall see.
Hope this is of some help.
