Well are you committed to the jump? As in you feel like you can do it. If you not committed you’ll never make it. Also what are you trying to break your record on? If your doing it on 3 pallets, you should probally not do that. You should find something at a height between 2 pallets and 3 pallets.
I wrote a tutorial on how to break committment issues, cause that’s what I used to suffer from. High Jump Tutorial for beginners by beginner.
Just keep practicing.