The EAA Chapter 663 Technical and Flight Advisors (Gordon Jones and Barry Weber) came out to have a look at N748PK before I put all the inspection covers, fairings, and seats back together. Much to my relief, they found a loose jam nut: it was on the right wing's bellcrank-to-aileron pushrod at the bellcrank end. It had inspection lacquer on it, but I immediately knew I left it un-trorqued after replacing the aileron. Syracuse's Law prven true yet again.
Next most egregious squawk: safety wire bass-ackwards on the left wings forward attach bracket. Oops.
But the most egregious squawk by a boneheaded builder award goes to: electric elevator trim wired up bass-ackwards!