volume problem with my sony portable

In a previous post, I mentioned that I've been using a Sony ICF S10MK2 around the house. A single pair of alkaline AA batteries lasted for over a year, with the radio being used for an hour or more on most days. I continue to use it mostly for AM, and rarely extend the telescopic antenna.

Now, even with relatively fresh batteries, the radio still occasionally exhibits a problem that I previously attributed to weak batteries. Adjusting the radio's volume sometimes produces scratchy noise, and the output volume is sometimes unstable. Does this problem sound familiar? I imagine that the volume control, which also turns the radio on and off, is susceptible to wear.

As proof that this is an imperfect world, the problem fails to reproduce while I sit here writing about it.