What Blockp said. It has nothing to do with turning the lock down bolt in or out,- unless when you tighten it, you also raised it up a few millimeters. It only adjusts rudder rake, as someone else said.

1. the lock down bolt has to have an unworn groove in it.
2. the bolt that goes across the casting can't be bent at all, (sometimes, you can turn a bent one downward, this tightens it up)
3. this same bolt, must move freely up and down. Don't tighten the springs too tight against the casting. I've seen a transom ripped out of a P16 at East beach, Galveston, b/c the springs were soo tight, when he hit the beach fast, it wouldn't pop up, and ripped the transom off!
4. after all this is done, then rarely is it the spring tension. New ones or modified ones as has been said then will help this.

Good luck