Played about 40 minutes. Played quietly as I have no remaining callouses whatsoever. No twinges of the thumb joints except when tuning and trying harmonics in left hand. It's basically the same motion so makes sense. My rt large thumb joint inverts when I try to play trills (creating a structurally unsound linkage), which may be why I was never any good at them. Wondering if PT strengthening exercises will help with that.