In case anyone else lands here, like I did, in the search for CO2 pot answers, I have a little more information:
The bottom panel can be removed, and the pot is actually a 43P502 - 0 to 5k, originally made by Spectrol (now Vishay)
Pins 1 and 3 (the outer pins) both have a 470ohm resistor on, taking the range from 470 to 5k4.
The part to replace the potentiometer can be found on Mouser or eBay easy enough - if you're handy with a soldering iron, its an easy enough job for a couple of quid of materials!
There are 2 of these parts (Ford: 082926) on ebay at the moment for £35 and £91 (yes that is a 9 and a 1!)
If you have a broken one you want to fix, I can put up instructions and photos and stuff, but what I'm seeing is the value is in the housing, so don't chuck it
