Bests & Worsts Reviews from Amazon

I really liked this cutter... until I put a stack of paper about an inch thick and realized it doesn't cut in a 90 degree angle. The papers that are on top are the size I want them to be, but the ones in the bottom are like 1mm smaller (see the photo I attach and you'll see what I'm talking about). I bought this specifically for trimming handmade books and notebooks... so its unacceptable the way it cuts. I tried adjusting the screws thinking that maybe the blade was loose or crooked, but it's still cutting diagonally...