Levitating light bulb, with a sound problem

[therwp]

A 17-second video showing the problem: . The first five seconds were videoed shortly after setting up the light. The rest of the video was captured about an hour later.

I bought the pictured levitating light bulb piece a couple of years ago. When the levitation effect is first started, the light and its 'stand' are silent. Invariably, however, after some time, the stand starts to emit a high-pitch sound, which varies depending on the location of the light bulb.

The problem existed from day one, and when I notified the vendor, they immediately shipped a (silent) replacement... but I still have this noisy version, and I was recently wondering what the problem is, and if it's something that I could fix.

Ideas?

[shakalnokturn]

Usually a coil loosening up when hot.