Contrary to Skor’s post, there is indeed a rule this this effect right there in the WPA rules.
1.12 CONCESSION
If a player concedes, he loses the match. For example, if a player unscrews his jointed
playing cue-stick while the opponent is at the table and during the opponent’s decisive rack of a match, it will be considered a concession of the match.
In the context of switching shafts (because of a tip issue for example) you probably wouldn’t be doing it while your opponent is at the table. And in any case I’d expect that players would understand you weren’t conceding if you had to switch shafts. That said, if I were playing with a hyper technical league player, I would probably announce “sorry, I’ve just got to switch shafts here” to avoid the argument.
