When you are attempting to hit between second and third arrow, where do you set your feet before you start moving toward the foul line in your approach?
Always starting on the same spot, will help determine if your missing your target because of drift with your footwork, or a misaligned swing and some funky swing dynamics.
Realizing that you target with your eyes but deliver with your shoulder/arm, determine from your favorite starting position where do you end up? Do you walk nice and straight (sliding and stopping on the same board that you started on)? Or do you drift a little, a couple inches left or right of the board you start on? or maybe just one inch?
Repeat your approach and delivery until you have a solid feel for what is happening. Throw a couple games and record each result. Where did your slide stop? Where did the ball roll at the arrows? Where did the ball go down lane? What pin(s) did you hit first?
From the middle of your body, determine how far over is the middle of your arm? 6 inches? 8 inches? 10 inches? less? more?
If your ball truly does not require grip pressure, it allows a free unforced swing. If you can depend on your swing; you can now aim with your body.
If everything is relaxed and aligned, if you start with your left foot (slide foot for a right hander, assuming right handed) on the twentieth board (middle board on the lane, the board with the center arrow on it, and the big dot on the approach) and the distance between middle of your chest and arm is 8 inches (8 boards over - each board on the lane is an inch wide) your arm should swing straight above the the twelfth board. If you walk up the approach with no drift, you'll slide at the twentieth board, middle dot at the foul line, deliver the ball up the twelfth board, but because you are watching to hit the thirteenth board (between 2nd and 3rd arrow) you might pull the ball just a touch.
Adjust the scenario for your specific tendencies (chest to shoulder 9 or 7 inches, drift a board, drift two boards, when you walk up the approach, left or right?). Once you determine what you do, you should be able to deduce why you miss?
If you drift right (and want to slide at 20, start two boards to the left, on 22nd board) adjust your starting point so you finish at the point at the foul line that you want to slide on/throw from.
The secret to bowling is a comfortable ball fit and embracing momentum and gravity to help deliver consistent shots.
Also, a slight bend in the knees at set-up with back fairly straight and shoulders square should help with balance. When aligned at delivery, the traditional player has head above slide knee, knee above toes. If your mechanics are OK, and without being able to see you throw a bowling ball, we may magically have a way to figure this thing out.
What do you think? Please post questions if you have them. Thank you.