I'd check the diode on the "R" (diode-test on your multimeter).
PIA issues can generate pretty random behavioural issues, and swapping them with known-good ICs (from another board, or new-stock) is always worth a try. They are always socketed, and it is unlikely you'll burn the good ones out in the swap. Good catch!
Great to see you're enjoying Pinside! Did you know Pinside is able to run thanks to donations from our visitors? Please donate to Pinside, support the site and get anext to your username to show for it! Donate to Pinside