Does anyone have experience with noise reduction ?

I know you have likely already done this, but is it possible that there is a loose connection somewhere in the system? Would another trip around the system re-tightening all connections of every type make any sense?

You don't by any chance have you audio system touching your video system, do you? Even if your tv is plugged into the same circuit as you audio, you can pick up a ground loop hum. I had a similar problem and it drove me nuts, I tried running dedicated lines, all sorts of power filters, but it wasn't until I put a MIT Iso-LinQ on my incoming cable line that the problem disappeared.
You could also lift the ground on one piece of equipment at a time until you find the offending component.

Good luck,
John

as john stated it is a video problem of some kind.first thing to do is check the cable coming into your house.9 out of ten times thats what it is. go to radio shack and buy yourself a ground filter its only 2 bucks.believe me after installing my very expensive system,which hummmed like crazy it was embarrasing to find out that a 2 dollar filter from radio shack cured it.check the cable and vcr and t.v.!!!

good luck harry