Tivoli Radio "Model One" Volume Problem

I love my Model One, but after I'd had it for a year or so, the volume control started acting up. It no longer goes gradually up and down...it seems to fade out at certain positions on the dial, especially the lower volumes.

I can make it work by sort of twisting high and low until I find a volume I like coming in clearly. Very inconsistent, and kinda annoying to find the "sweet spot" for whatever volume I want.

By the way, I wondered if this was a function of the radio setting, but I hooked up my iPod to it and it did the same thing (though I could more fluidly adjust the volume with the iPod control in this case).

What do you think?