I have straightened shafts at times. But rarely do they hold straight. About the only ones I saw stay straight were newer cues that someone bought and then noticed a wobble in it within a few weeks. For some reason if you catch it early in the cues life like that and you straighten it on a table by bending it then, immediately sand it on a lathe and reseal it, they might hold. I learned that trick from my days as a pool room owner selling other brands of cues. If the shaft has too much time to develop that bent memory you will almost never get it to hold straight again. It is kind of like us humans; If we stay in a bad habit for too long it almost takes a miracle for us to get straightened out again and stay straight.