I have not checked the bearings, but YS replaced the rear bearing. I assume that they would have replaced any bearing that had a problem. I did fly it today without the cowl and it did run a little better. At least it did not lose power like it had been doing while in a hover; it still will not pull out of the hover like it use to...maybe it's just worn out??? I may try some 30% heli fuel and see what that does instead of the 20% Pro Pattern that I normally use.