Often I like to look for alternatives when futzing with creative stuff. I jumped on Digi-Key, added a couple filters for you, and here is a link that should allow you to find a suitable replacement pot.
Potentiometers, Variable Resistors | Rotary Potentiometers, Rheostats | DigiKey
First you need to know what the original pot resistance value is, which requires an ohm meter connected to the 1 and 3 posts of the pot. To make sure you have the correct 2 pins, turn the pot. If the value on your meter changes, you have one of the pins wrong. Select that resistance value in the filter window, then click "Apply All".
Next, you can filter your shaft length. You can keep adding filters to reduce the 4950 selections down to a page or 3. Hope this helps.
