ACTUALLY, if it ain't shooting well, then you DIDN'T re-tune it well. The problem's more likely the guy behind the bow. Even an OUT of tune bow unless you have MAJOR fletching contact issues should group fairly decent. The LOOP should give you better control, and if you set a nock above the arrow, it will push the arrow down into the rest so it doesn't try to "jump off of the rest" when you draw the bow. I just recently switched to loops on 3 of my 4 bows and my shooting is better than before w/ FPs and BH's right with each other at 40 and just slightly varied at 50yds, but that is more shooter than bow as I can't focus as well as I'd like at that distance.

If you changed string just because your center-serving was roughed up, your pro-shop misled you. A simple replacement of the center serving, unless you'd broken some strands, would have sufficed. I'd replaced my center serving 5x on a set of strings before ever needing to buy new strings. And I only needed to buy new strings because of my own neglect to wax them as often as I really should, and maybe a little desire for an upgrade over the 2 1/2 yr old factory strings that had been re-twisted several times.