This is the attenuator I was using:
http://cgi.ebay.com/Adjustable-TV-UH...item518baade82
It seems like the MIN side is mostly the same as what I have without it, and the MAX side gradually turned it to distortion and static. Referring back to your previous post about these, that sounds about right. So yes, the MAX attenuation results in a more snowy picture and finally nothing but static. The buzz was present when a picture was present, past that it's all noise.
I'll have a look at that pot when I pull the chassis out tonight. Honestly, I think it was the steel wool I used awhile back. A little shard of it must have rubbed off in there when I was doing some light polishing on a part of the chassis back there. Guess I won't be doing that anymore.