Can we find out a bit more about the circumstances surrounding the first appearance of the problem - where were you flying at the time and what were you taking off and landing on; ie what is likely to be in those gimbal motors obstructing them ? If it is dry particulates of some type then you could maybe try clearing it yourself with some precision application of canned air. And obviously you need to identify which motors have the problem which you should be able to do to some degree by moving it slowly by hand in each axis individually until you find one or more that feels 'grainier' than the others.