Thanks so much for weighing in, Aaron. I just measured again from the end of the nut to the middle of the 12th fret and what I get is about 25.45 mm on both the first and the fourth string. Not sure if I'm measuring exactly enough, though.
What do you mean opening up the saddle?
Simple math tells me you'll have 25.55 from your 12th to the saddle. I'm going to guess this is in cm, as you have 510mm total scale length. That's 1mm of compensation as anthonyg alluded to. Sorry, I work in inches, so about .039" You
should be okay with that, but obviously you're not.
First thing I'd do is be sure your saddle is as close to the neck side of the bridge as possible, on the first string . If not, get a new saddle, compensated. I can't tell if the crown is right at the edge or if there's room to go. I'm thinking new saddle. BUT, before that. . .
I'd also try on a thicker set of strings, or at least an A string. Personally, you went the wrong way with Worth.
Opening up the saddle means recutting a 3/32" slot to 1/8", towards the neck side since you need to shorten the scale length. Surgery for sure, but if I were to do it, I'd fill the slot, then recut it with Rick Turner's 7 degree angle. Of course, that may defeat the purpose because it would actually stretch the scale length back out, so forget I said that.
I realize none of this may be the easiest, but you asked in this forum for a reason.
Note: If your intonation is good going up the neck, but your open string is off, I'd maybe take a look at the nut. Joe's been doing this a long time, I doubt if its there.
My guess, its your strings. I know he used to put Aquila's on stock, and while they have their place on certain instrument, I've always thought they limited what I hear from Joe's instruments. Sometimes, production makes you do production things, and that's okay. Strings are cheap.
I just checked Strings by Mail, and the D'Addario Titanium T2's are what I use on some of my Spruce tops. Funny, the Tenor set first string is .029, while the Baritone set is .028. You can order them individually, T44/T45/T46. I'd put money that the T4401 may help. Of course, at $1.62, that's about all the money I'd put
Damn - this must be a record longest post for me. . .