Volume control Jumping when adjusting

[Tarydesign]

I have finally decided to pull out the radio and check what causes the volume control to jump (sometimes in the wrong direction) when you adjust the volume control knob. This seems worse when you start the car and for the first 10 to 15min things are at the worst, thereafter the volume seems to work just fine. I have noticed that many MLs have this problem, my ML270 was sorted out under warranty by the dealer, and every ML I have test driven has this problem to some degree.

Car: ML430,
Location: South Africa
Radio: Audio 30

Does anyone know what the problem is? Can I just pull the radio out (with the two radio levers)? What do the two levers look like, I have a few I'm going to try, but is there something special about the ML ones?