If the VPI forum is still active, might be worth searching. Reaching out to VPI is in order too.
Are you using the VPI protractor? If so, it's supposed to be a distance that's somewhere between Stevenson/Baerwald. If you have an aftermarket jig, perhaps try Baerwald, which might push the cart more forward?
I've read random reports some cart brands for whatever reason just won't cooperate with any amount of fussing.