Does anyone know what can cause the up/ down control to operate by its own or which part may need replacing? By this I mean that the motors start as normal but when the UP stick is used the drone takes off and goes to full power without reacting to the down stick. Eventually the down stick kicks in but then it is a mission to try and land in one piece as the power comes and goes very erratically. Have been flying for 6 months quite happily when the V2+ started dropping altitude mid way through flights and not immediately responding to UP stick. This caused several hard landings and bounces off the ground. Have checked everything with RC & Vision assistant, re-calibrated everything inc adv IMU but no difference. Daren't fly now until I can make it work properly without the props on. Any ideas please?