How do you hold your catty Gavin? Forks up or forks to the side? If forks to the side, then I used the tip of the fork as an aiming marker, and using my ear as an anchor point to pull to, might be worth hanging a piece of paper up with a 25mm black circle drawn on it, take a few shots at it, holding the catty that feels comfortable to you, then you will be able to see how far away from the circle you are, then adjust from there. If hitting high of the mark then raise your anchor point, if hitting low then lower your anchor point, then if your hitting right of the circle then move aiming mark