With having so many old cues from the sixties and seventies some develop a bit of a warp to them, I have had to get the joints faced off several times.
This is done with a cone in the bumper hole so the entire butt is aligned from the bottom of the butt sleeve to the joint pin. as it turns you cut off the high spot created by the slight curve. it is amazing how much improvement you can get this way.
I have had a few cues that flopped like crazy end up with only a tiny bit of wobble when they were finished, and when sighted like a rifle you can barley detect any variance if any at all.
If your in the Denver are go see Ernie Martinez. He has worked miracles for me making otherwise dead ones into perfectly playable cues.