Every now and then the S-meter on my R8B will 'take a nap'. The needle
will come to rest in the far left position and will be unresponsive to
signals.

It's easy enough to fix this. All I have to do is rotate the gain
control clockwise and the needle will spring to life again and work
just fine. Still, I'm curious about why it happens.

I'd say it happens about once a month.

Any ideas?

Steve