What causes a potentiometer to get "jittery" after cleaning?

I recently cleaned a potentiometer’s resistive element by using general purpose contact cleaner (CRC). I now find that there is "jitter" or non-linear increase in the resistance as I rotate the shaft. For instance, the resistance might momentarily drop while increasing the resistance, but this only appears to happen if I rotate quickly.

I’m curious what causes this as I suspect I may have damaged the resistive element on the potentiometer. I cleaned two potentiometers with the same cleaner and the effect is present on both (one worse than the other).

For reference, I am working with Atari Paddle Controllers, which are basically a potentiometer and push button. The game input and jitter was tolerable prior to cleaning, but now it almost makes the game unusable; the in-game paddle/icon jumps all over the place as the physical potentiometer is rotated.