I sent my copter to the dealer (multirotorheli Calgary) to get the thing fixed.. The guy claims to have replaced the gps unit.. When I got it back, I noticed it went into a major toilet bowl effect, when I lifted off.. But here's something new.. And by the way: the compass is calibrated to within the listed parameters, plus I did both the basic and advanced imu calibrations.. When I fly in a straight line, I'm back to the major left slide, and left drift after stopping .. But I noticed when I let go of the toggle, the copter keeps moving straight ahead for sometimes 30 or 40 feet more, before going into the left drift.. Why would it do that? At the time I had 9 satellites locked. By the way, the copter definitely flew better, when I had rotated the compass about 17 degrees clockwise (as viewed from the top) = to my current +17 degree declanation.. I have since moved it back..