MPC 500 Slider and Volume replacement

My mpc 500 has a faulty volume knob. It makes a really loud computer hum which goes away when i push the knob to the side. Has anyone else had this? Any cures?

Also wondering if anyone has replaced the Slider and Volume board? Is this easy to do?
Found a part here: http://www.mpcstuff.com/1atwpc06a003b01.html

Its a defect, exchange the 500 for a new one. But if you can't then make sure a certified technician installs that. You could fock it up further IF you never done something like that.

www.vstservice.com is cheaper and easier to pay with PayPal.