I hate to sound like a broken record, but w/ Mathews bow's Idler lean is the root of most bad tears and tuning difficulty.
I owned a SW and had the identical problem. It didn't rear it's ugly head till I tried to tune broadheads. fortuenately it's an easy fix.

At any rate make sure your axle to axle is exactly 31" on BOTH sides. A twist or two of the yoke on one side or the other should take care of it.
Next set your center shot at about 13/16'' and make necessary adjustments from there.
Your bow is a real shooter and I think this will fix u up.