What break points have you tried to play? To borrow some terminology from Ron Clifton, have you tried using a break point in all three zones? 1-5, 6-10, 11-15? Have you tried getting to each of those break point zones from three different laydown points, outside (5 board) middle (20 board) and inside (35 board)? Have you tried playing the twig (can you play the twig?)? deep inside angles? When you say "I've tried it" do you mean a couple of shots with one ball, one speed, and one release? Or do you mean several games switching out balls, speed, release one at a time in a controlled experiment approach?
Conquering a challenging shot should be a challenge to a competitive bowler. Non-competitive bowlers really won't care. Bowlers that do care and want to conquer will keep searching until they find something that works.
Sure, posting here might gain you some opinions on different things to try, but it is impossible for anyone to render any real help not knowing how you throw the ball, your true accuracy level, the surface, conditioner, consistency of the lane machine, etc.
In other words, first-hand experience is going to be your best bet.
When you get the feeling of "it's not working", which you describe, it is time to try something else.
If you're not willing to change, you're not willing to improve.
Good luck - I look forward to hearing that you succeeded and what it took to get you there.
--------------------
J.J. "Waterola Kid" Anderson, the bLowling King : Kill the back row
Edited on 8/6/2008 8:38 AM