I installed four new Tiger motors today (because I could not find replacement stock motors anywhere). First few flights were fine. Motors are very high quality. Can't tell much of a difference in performance other than they are quiet. Problem now is when in GPS mode only and I give it throttle, it pulls hard to the right every time. It does not do this in attitude mode. I have reset the compass multiple times and recalibrated multiple times. Any ideas what might be causing this?