Reply to Replace AKAI LPD8 Pots?

Hi,
After having problems with one of LPD8's Potentiometer (bad tracking after a year of heavy DJ use) i decided to open it and check what's goin on..In my surprise i saw plastic Potentiometers so i decided to look for better quality to replace them but the guy at the electronics store said that there are special ones (it has to do something with the voltage don't know much..).Does anyone know where i can find better quality Potentiometers (maybe something metallic like that http://upload.wikimedia.org/wikipedi...entiometer.jpg) so i can make my own custom tank LPD8?
Or do you know any way i can stop pots from wobbling and get better midi tracking?