Its only on 3 motors. Louder clicks on two of them.
We dont see the movement, just hear this distinct click that sounds a lot more through the frame standing by it self, than when holding the boom with one hand. Maybe I should YouTube it some day. I have had movement in motors, but no clicking sounds. Some props have got in the lawn when we had the tilting problem in the beginning, but that wasnt much rpms and they didnt stop like buried into the ground, only dirt on the tip. The arm rested on the lawn.
No transportation problems as we know.
The motors were used when we got them, so we dont know much of its previous life. The rig with the motors werent crashed.
Not so salty water around here, but we do live on an island. But thats not any problem.
By the way, this rig is doing its job very good, flying now and then (even in the cold), very satisfied (building a similar X8 now, all new parts including the motors).
But as you say, nothing to worry about now.
New bearings when needed.