Originally Posted by neftaly
Are you sure it's supposed to be 50k? It sounds like the resistance is too high. That spike at the end is where it's metal-on-metal (0 ohms).
Is there a model number on the controller board or something? Otherwise get someone with a multimeter to test the old pot.
At the 20k ohms setting it ranged from zero to about 5. That's 100k right? Wouldn't that be even more drastic of a curve based off of what I saw with the 50k.