Hi, The motors in our FIRST kit, I think there called CIMS, well when we constructed the gear box we followed the video, but it seems one of the berings on the back of the gearbox (where the motor is) seems to rotate. It rotates in the whole which was drilled with it. Right now we plan on utilizing lock tight to fix it, but has anyone else had this problem, and did you solve it without using locktight ?
We have had to deal with a similar situation in which a bearing had a loose fit in a hole. We mixed up some standard two part epoxy, smeared some in the hole and smeared some on the outer race only of the bearing then assembled everything together as usual and let it sit to dry. This would not be the optimal solution but it is what a mentor on our team calls “Friday afternoon engineering” 
Isn’t it wednesday tho ? lol :D. Thanks for advice, ill pass on the knowledge