Newbie here, so bear with me. Picked up a used Q and it's drifting pretty badyl. Checked the hardware monitor as suggested by other members. The J4 is way off as this pick shows. How do I fix it? I tried wiggling around the sticks but no luck?
Give it a vigorous stir then move the stick slowly and see if tracks your movements without jittering. Then more more quickly and watch for it lagging behind your movements. It should return to zero position when released.
If it is still giving trouble after the vigorous stir, then use a plastic safe electrical contact cleaner to clean the potentiometers on the control gimbal. You need to open the case to get at the potentiometers. Instructions in this post Got a Warning.