Jon,
Don't compliment Tim on his fine looking Aldridge too much, I don't want him to get any more attached to it than he is.
That set used to be mine and I parted with it before I was hooked on collecting 21" color sets. I got it from the original owner. Now I'm trying to get it back!
It looks way better now than when I had it after Tim cleaned it right up, especially behind the glass.
Christmas treeing probably is more commonly seen in B&W sets. It is when the horizontal frequency gets way low and you end up with a central vertical zone with horizontal branches out each side different lengths like christmas tree branches.
Rob