switches
If your propane level indicator is the same as most, the switch is a normally open, spring returned to open design, or momentary. The propane level detector is just a magnet attached to the pointer of the float level indicator that is on/in the propane tank. The magnet moves the wiper of the detector to send a signal to the indicator panel. It might be either a series of lights, or a meter movement, depending on your display panel. If you don't have one, I suggest you get a cheap meter and check the switch with it first, to be sure if it works or not. The ohm scale should read near 0 ohms when the switch is held closed and at least 5k when in the open position. It should read a voltage to the detector side of the switch when not depressed, if the wires are good. You may also want to check the indicator lights as well. If you give more specifics about what you have, we might be able to help more. The switch is probably not made by the company that made the display, but you can very likely find one that would work at an electronic supply house, or possibly even at Radio Shack.