Or at least I think it was the 6lb6. I took the tube out and it does have a rattle when I shake it near my ear. Sounds like a burnt out light bulb. I can't see anything inside though. I do notice that not all the pins are connected. I can't verify which tube is which though as there are only zenith #s on them and the schematics is new to me. I put it bak in and it seems ok....for now.
From earlier threads it would seem that the flyback would have some affect on the picture. The picture seems fine whenever the noise is there or not. In fact the pic is as good as any of the "new" TVs I have.