Wolf Super Endpin - slippery on wooden floor

I think it took a while for mine to get less slippery... It might have been a a month or so after a bunch of gigs on bare concrete, if memory serves...

This is just an idea, but maybe you could try scuffing the bottom of the ball with some coarse sandpaper...

 

Using it on concrete might rub off the rubber rather quickly.
Maybe good at the beginning to avoid slipping on smooth grounds, but if you do it too often you might get a hole at the bottom (like on mine).

Currently I change to a traditional rubber pin end for transport, but if I buy a replacement, I will use the one with the hole for transport and the new one for playing (unless the old one works better in some situations) by just changing the rubber ball.

Unfortunately I haven't found the rubber ball without the metal assembly as a part yet.

 

I stand my bass on a small piece of carpet (8" (200mm) diameter) with a piece of silicone anti-slip mat glued on the back.

I just have to remember to take it to rehearsals!

 

Wash it with some simple green cleaner. In one of my other past hobbies (racing R/C model cars) we used simple green to condition rubber tires; made them sticky as all get out. Should work on the ball as well.