not that this will definately help, but the yoke only needs to be twisted up on 1 side so that the string is coming off the cams straight at full draw. to correct the lean while the bow is at rest is a major mistake that many folks seem to make.

are your cams hitting atfull draw at the same exact time?

are you using a drop away? i'm guessing off the top of my head that that is the real culprit. often times they bounce off the shelf and hit the arrow.

before giving up i'd try a different rest at the shop, preferably a prong rest.

as a last resort its possible there is an issue with one of the 4 limbs or a limb pocket.