Welcome to VAF.
Paul, if it's a rigging issue, you squeeze the aileron trailing edge with a pair of wide jaw vice grips, or possibly your fingers, of the LIGHT wing, in your case the left wing.
Be sure that the ball is centered when you fly it to test and also that both tanks are equally full.
Only squeeze a short 2 or 3" at a time and go fly...repeat if necessary.
Best,