I only had to raise mine about an eighth of an inch, but it depends on where you started. I'd try 1/2 inch above the shelf and move up or down from there until you get the arrows hitting where you want them and stop bleeding! I'll go check mine a minute, but yours may be way different depending on your bow.
Some use toothpick, match sticks, leather, foam. I only had to do it on one bow and I used leather shoelace trimmed about in half. A little bit can make quite a difference.