I had the same problem, but my groups were good at 20 yards and at 30 yards they went to the left about 4 inches. I use a center shot gauge and my center shot was right on, so I moved my shoot through rest to the right about 1/4 inch and my groups were good at 20 to 35 yards. My paper tune are now bullet holes and the bow is more accurate.
I've noticed that sometimes you have to move the rest off center to micro tune.
Before buying a new rest, move the rest in about 1/4 inch, adjust your sights and see what happens. Get your steel heads on target then try your field points, sometimes by doing this your field points will hit where the steel heads hit.
If this doesn't work, then It's probably your rest.