Just got a Hubsan X4 H107l after charginging the battery, calibrating the gyros I took it for a test flight. Was inside so wind wasn't an issue. It flew level on take off with very little stick needed to keep the heading. The only issue I have is the yaw drifts to the left. It will go to the 11-10 o'clock once or twice it went always to 9 o'clock. If you hang on and keep flying (which is hovering for me) it might return to 12 o'clock. According to the manual to trim the yaw you land it for 3 sec. This had no effect on mine. Tried Google to see if this was an issue or maybe a fix. Nothing and nothing was mentioned in any of the reviews I read or watched. So I'm trying to figure out if I have a dude or that's just the way it flies.