I accidently had a small knock (very minor) when taking off my drone bag, and one of the motors feels like It has a considerable amount of play on one of them, im just worried to fly it now as I don't want any motor friction issues. have I possibly just knocked the motor housing? when I spin the motors by hand they all sound find apart from that one. Has anyone got any suggestions? Could possibly be a bearing issue? Has anyone had experience changing the bearings themselves?