I just got my phantom 2. I flew it a couple of times for under 5 minutes. 4 flights total. I finally got it out in a open field and let it soar. The phantom did great. went home and then about an hour later went back out and one of my motors refused to spin. When you manually spin it theres like a grinding noise inside. No metal flakes just rough to spin. Any ideas? I tried putting some oil in the bearings but i was unable to get to the bottom bearing. I didnt have the proper allen tools. Iv read on sites that the bearings suck and replacing them is what most people do. I was unaware of lubing and maintenance required to the motors. Is that something you guys do before every flight?