RE: tuning question
You may have a tuning issue, but could be other things. Assuming your arrows are correctly spined and your bow is within its specs, and your form is good, etc., the walk back test is easy enough. This is how I do it.
Draw a vertical line on your target and shoot at a specificspot on that line, preferably in the middle of your target (to to bottom). Start shooting at 10 yds, but use your 20 yd pin (as long as you won't shoot over the target)and establish where your arrows are grouping in relation to the vertical line. Then move back to 20 yds and shoot the same pin at the same spot on the line. Repeat at 30 yds, again with the 20 yd pin.
If you see that your arrows are impacting to the left as you move back, move the rest very slightly to the right and repeat the exercise. Do the opposite if they hit to the right as you move back. The goal is for your arrows to fall in a vertical line as you move from 10 to 30 yds.
Once you get that to occur, move the sights leftto rightto get your arrows hitting where they should.
If you are still seeing that yours arrows hit nock-end left, it can't be blamed on your rest position. I'm sure there are many possible explanations, but I'm not the guy to give you that advice.