A very common rigging problem is that the lateral pushrods for the ailerons bind in torsion near the ends of up and down elevator movement. There is just enough rotation between the two rod ends on each lateral pushrod to accommodate the angle of rotation of the control stick assy. between full up and full down elevator.
The quick and dirty test for this is to lift/lower the elevator at the tail, noting if it feels like one is fighting a spring near the up and down extents (this "spring" is torsional deflection of the lateral aileron pushrods...). One should not have the stick boot in during this test. The more focused test is to verify that each lateral pushrod can be still rotated a tiny amount when the stick is at each corner.
This problem has existed in almost every plane I've inspected prior to first flight.
RV6A N66AP 1600+ hours
Maple Grove, MN