I am only on day 3 of the phantom but in GPS mode it used to hover in a tight little area fine and if you throttle it forward it would pretty much follow a straight line as well. Now I have to semi actively keep it hovering in place as it will slowly drift and also it drifts while trying to fly in a straight line. I recalibrated it via the software which did not solve it. I am making sure to get a homelock and greater than 6 satellites every powerup. I did take a couple of minor dingers while taking off and landing which caused it to faceplant into the props. Nothing major, my momentum wasnt completely stopped. I also ran into a bush in my backyard during practice. I wiped the dirt off but the props do have some dings and scratches. Is it time I invest in the prop balancer? Will unbalanced props really have that much of an effect as to throw everything else off?