Thanks to Richard (RLSharp) and his great information, I decided to remove the dial module today. 2 screws holding it and it popped right out. My screws seem to be SS steel; came out with ease...looked like new. The dial is totally sealed and would be a cinch to replace if anyone needs to do that.
I cleaned up the unit, then used a magnet (as Richard suggested) and found that the needle could easily be moved from min to max. Next ,I attached my Ohmmeter to the terminals and found no resistance (infinity). (No wonder my LED showed full all the time).
Next, while having the ohmmeter attached I used the bar magnet to move the needle from min to max many times. (All this with sitting in the RV with the dial assembly in my hands). The idea was to move the slider on the variable resistor back and forth many, many times in order to clean that microscopic contact with the resistor film. Well, guess what; soon the ohmmeter started to register readings. After awhile I got the proper readings, 0 (infinity) to 100 ohm and anything in between. That told me that the unit was not defective, rather just old and tired.
I then re-installed the dial on the tank and lo and behold it read the proper tank level on the LED display. But here is a caveat: The needle is propelled by a small
magnet inside the tank, which moves the needle as the level of propane changes. The problem is that if your tank level sits at a certain level for a long time..in my case for several months.. it will take a somewhat major change in level to move the needle to another resistance value.
In order to get a true reading, I decided to drive the RV for a bit in order to slosh the propane around the tank a bit. That seemed to do the trick and gave me an accurate reading then.
So, Richard, I really don't need your sandblasted unit after all. Now that I think I fixed
it, I'll report in again after real time experience.
That's the best I can do, folks ,in explaining that horrible problem.
carson FL 79.2°
Edit: One item I forgot to mention.. the four major screws holding the big assembly in place, I was able to tighten them about 1/8 turn each. Wonder what kind of seal they use. No propane leaks ever detected.