Not much to say here besides clean, clean, clean! Once the ball gets dirty and oily, the coverstock loses its tackiness. You need to restore that tackiness. I clean my stuff every time I go bowling. I have much older equipment and they still hook great.
As for the cleaning, if you do some searches on here, you'll find a lot of info on some different ideas. For after bowling, I use an
Ebonite cleaner, bought a big bottle around 3 years ago, and I still have a good bit left. In your case, you need to get deeper into that ball. I'd recommend the hot water/dish detergent bath described on
MoRich's site, I did it once and it worked really good to get out the real deep stuff. If that doesn't cut it, I'd take it to the
Pro Shop and have them rejuvenate the ball. Personally, I'd stay away from any methods that involve possible excessive heat, you don't want the core separating from the coverstock.
Hope this helps.
Mark