Crazy colume control in Pioneer receiver

Hi,

I have a Pioneer VSX-D309 receiver that was woking nice until
recently, when the rotary volume control became kind of crazy. It now
performs erratically, so for example if I turn the volume down it may
actually go up! Or it may "jump" directly from, say, -60 to -35dB. The
remote works smoothly, though, which suggests a mechanical problem
with the rotary control. This control is not a potentiometer, it's a
kind of a continuous digital/optical control. Any clues?

TIA, Rubem

My goodness,that IS strange
sounds like a trip to the repair depot is in order, alas

JB