I performed the following checks with the engine off, servos on. All appear to be correct.

Confirmed all linkages at 90 degrees
Mechanical throws appear correct
end points mechanically set

Aileron-functional
Elevator-functional
Rudder-Does the rudder servo need to be reversed on the controller? Although I don't believe it would cause this type of issue if it wasn't.
Collective Pitch- Swash-plate level with full collective
Throttle- is in conjunction with collective pitch (servo reversed)
Gyro- performed perfectly, heading held, no REVO mixing required

Pitch and throttle curves not yet calibrated, set to controller's default.

I notice the the main blades will loosely flop back and forth, I'm assuming that this is normal and that they hold their pitch with centrifugal force, and it appears that all linkage is in place as the person that built it last winter left it.

Any ideas???