the tendency of a single cam is to pull the nock down when firing. that's why if you're getting a high tear its probably from contact by your fletchings or the back of the arrow and the rest/shelf/something. i'm trying to think about a drop-away on an overdraw, that doesn't seem to have much arrow to get out of the way. i mean, you don't want your drop-away falling immediately, it needs to stabilize the arrow a bit. i don't have any experience with overdraws and drop-aways, but they can be really finnicky right at the shelf and thinking about one 2" behind the shelf and the tinkerin that could take is givin me a little headache like nodog said, footpowder, or just move the nocking pt up or the rest down (if its not going below the shelf) and see if the tear gets better. like i said, i've never tuned one with your setup, but i think you may be in for lots of experimenting and many sheets of paper.