Here's the natural position of my gear shift knob when screwed on until snug. With the gearshift at "high noon," the knob was way too loose. Unscrew the gearshift knob all the way, counterclockwise. Hopefully, yours will easily come off. If not, removing it may damage it and you will then need a new knob. For a really stuck knob, a plumber's pipe wrench works about as good as anything. You can wrap the knob in a towel but that probably won't prevent tearing up the knob by the time it comes loose.
I have tried different materials - rubber, paper. This is a scrap piece of green felt from under an old battery terminal.
I get a kick out of using old scrap pieces to fix things, which in my mind justifies not ever throwing away anything Z related, lolam.
Felt is compressible, and it doesn't degrade or come apart like the matchbook covers I used in the past. I cut off the small piece of the inner circle that is missing in the above pic, and rolled it into a tight ball.
I stuck this tiny wad of felt deep into the hole under the gear shift knob, then screwed the knob back in place. Don't try to end up with the knob being too tight, just snug enough so it won't move. If you turn too far and then try to unscrew the knob, you will loose the tightness and probably have to start over.
The best way to remove the old felt is to stab it near the edge with a pick, and then unscrew the felt until it falls out.
Gear shift knob is straight and tight, take my word for it ;c)