Help? My theremin is suddenly very quiet

It still seems to make all the right noises, but the volume on both the theremin and the amp has to be turned right up to hear anything at all, and it's still very quiet.

There's definately not a problem with the amp or cable.

It's had no knocks or bumps, the only thing I can think of that's been different recently is that it's been moved slightly, nearer to both the window and the radiator - could temperature fluctuation cause this kind of problem?

It's a Moog Etherwave standard.

Any advice would be appreciated.

If the volume loop is near the metal radiator, that would tend to cut the volume level. (I once inadvertently silenced my instrument by setting it up on a wooden table, with the audio cable running directly under the volume loop.)

Thanks for that - but it turns out it was actually the cable all along.
I feel really quite silly now for having such a panic about it. ><