I cant remember how much I had mixed in I do know it is nothing like 20%, it would be some thing like a couple of degrees. I would suggest take it all out and then during the next flight put your flaps in and throttle down as if for landing, get a mate to monitor how much elevator you are holding for a level flight, then program the same amount in mixed with the flaps once you have landed. She will landing quite happily without flaps just a longer approach and landing.