Could be the balance potentiometer itself. They are inclined to get worn or dirty or both. Does the sound come back if you wiggle the balance control?

That won't work Jay, we must have 10 remotes scattered around the house!

Just replace the offending woofer. You need to be solder handy as the new speaker will come with some components to update the amp to latest spec. Full instructions are provided for this together with instructions for re-calibrating so the system works to spec. You need some form of DVM as well. New woofers are ~£30

She Who Must Be Obeyed = SWMBO

Brett (beo4life) and I fitted a motorised wall bracket and an MX4000 in my bedroom at the weekend. Will now be spending more time in bed!! Sad, I know. Only trouble is, SWMBO now wants to watch her crappy programs. 40 years ago I was desparate to get her into bed, now I'm not so sure!!

He wants the service manual Peter. He has a 9000 with a problem and I daren't be without mine.

Just for the record, Neil knew the tube was duff when we did the deal. In fact he diagnosed it!!!

I like your suggestion Lee, funny and express the meaning or emotion well.

The only real way of checking properly is to take the covers off and look. However, it is possible to shine a bright light on the fret and see through it but the view is not that good.

I would leave well alone and stop looking at the back of them!! The problem with polishing is that you will destroy the anodised finish over a large area and it will never match the rest of the cabinet. So, instead of a small mark you will end up with a big one.