"... rerigging them [ailerons] to be streamlined in flight is not going to change how they perform in flight."

It is a common OEM procedure to intentionally "mis-rig" ailerons to account for "float" in cruise (normally with newer, more aftly loaded airfoils, though). It is also common procedure to mis-rig both ailerons up to unload the outboard wing (increase twist) or both down to load the outboard wing (decrease twist). It is more common to mis-rig ailerons up to produce better stall characteristics (inboard wing will stall before outboard wing). Rigging of ailerons should be independent of control system forces and cable tension (it's a "balanced" system). All flight controls (in this category of airplane) should move lightly and freely on the ground. As others have suggested, check the entire cable routing, you might find that a cable is rubbing or has come off a pulley. I'm looking forward to hearing what you found out at the airport :o)