Pin box is rubbing on hitch

I think that would hit on a 16K Reese hitch also. Am I correct that you had this hitch on another trailer before this one? I'm wondering if the bolts and all the holes fit tight. If say the pinbox was made for 5/8 bolts, but you only have 1/2 bolts because that what the trailer is sized for. If that were the case then the pinbox could rotate a few degrees, pushing up in front. Changing the geometry by a small amount. The fact that your hitch plate isn’t level makes me think the pinbox is at the wrong angle. The other thing I would check is the pivot bushing above the pin.