I'm overseas and away from my workshop (AKA the unused corner of the furnace room), but I just had to do something about this intonation thing. It was driving me nuts, micromanaging my intonation (try remembering to finger normally on E and G, and flatter by up to a semitone on D and A, depending on where you are on the fingerboard). With pieces with lots of double and triple stops... don't even get me started.
Anyways. With some not-quite-the-right fit tools, I lowered the D and A strings pretty much to the limit of playability, and adjusted the nut for the extra width on the D string. It's high time for me to make a new bridge anyways, so it doesn't matter much. However, the D and A are STILL sharp---even as low as third position, fifths start getting real wonky.
No, it's not the fingerboard scoop/ neck relief. An actual luthier has played this instrument before and didn't have any complaints.
I emailed Pirastro, though, and they did send me a free, fresh set of Chordas. So, yay. Now I can prolong my suffering. Or pawn them off on my worst enemy.
Adalberto, from other posts I guess that Cotton simply is someone who enjoys tinkering. Sometimes I understand what he is trying to achieve, and sometimes I'm not completely sure about his intentions or the underlying problem. Like this time...