2x ball dosent roll straight

[wun]

I guess I did not explain the situation quite right:
When I say it dosent roll straight, I mean REALLY not straight. Like, you give it a push (even a hard one) and it will roll for a little while, then sometimes make a 90 degree turn, or even roll back to where it came from.
This is much more than the ridges or plug could do (we are using a bolt as a plug, and when the ball comes to rest, the bolt is on the side, no where near to the bottom).