I got down close behind to see what's going on, and the event happens randomly, and is also accompanied by a sort of clicking sound inside the amp, like a solenoid or something... It soudns like the same internal "click" I hear when I power on or off my stereo (not through the speakers).
It does this on both channels regardless of whether the guitar or cable are plugged in.
There is also a new randomly intermittent buzz and sound which I noticed before it started popping.
I read in another post about somebody having a very similar problem and a reply suggested a voltage issue, maybe in the house or neighbourhood... It's an old house and the amp is plugged in on a chain of multi-plug splitters that's not recommended, I know, but again, I've been running it in this configuration for years with no problems.
Thoughts and test recommendations welcome.
