Kind of odd that it would be all the way left on one flight and then be to the right on another. I would mark the location of the pot and play with it. I have a Eflite Blade CX and have it adjusted so that at the beginning of a flight it flyes just fine, but by the time the battery is done I need to give it rudder to keep it straight. You might even try just turning the pot lock to lock and putting it back to where it was and see it that helps. Sometimes pots can get dirty and moving them helps clean them up. Jeff