The invariable question that you'll receive is why are you doing a 1RM PR? It's certainly not part of the LP program. Perhaps you've moved onto intermediate programming. I will assume this.
As far as the pull, you need to squeeze your chest harder. You're pulling with bent elbows. This is not good for your supinated arm and can lead to biceps tears. No bueno.
In what you probably assume is squeezing the chest, you're dropping your hips. See how they drop and then once you start pulling they shoot up? They need to just stay in that up position from the onset. Think about spreading your chest to the wall in front of you. Hope this helps.