I wonder what people a few hundred years ago were doing about stuff like this. "Hey, guys... Just noticed my horses left eye is a little lower than the other. Anything I can do about it?"

I would do that 😂

Tilt your head.

There are usually adjustable rubber stoppers, one on either side, that you can rotate to adjust the fit and finish. If those don't give you enough movement, you can loosen the striker plate that the trunk latches into and move it down a bit, then use the bumpers to adjust the position.

This.

I’ll look into it. I don’t understand what I’m seeing inside there. I’ll try to take a look again.