I opened my grind machine to look whats inside and took the axle off. I took off the hubstack (meaning one) and I accidentally took off the o ring. And the bearing is stuck into the hubstack itself. And it is impossible to get the bearing out. I put back the whole habstack (including the bearing) but it keeps falling off. I know you have to put the o ring back on but it is impossible!!!
Try using tweezers and make sure you are putting the hubstacks back together in this order: bearing, o-ring, then plastic stack.
The bearing is stuck 2 the plastic hubstack part thing 
You can use the tip of a pen or pencil to push it out.
when my bearing comes off with my rice stacks, I just use the yoyo’s axle to push it out from the other side. (like through the whole on the top)
@mrcnja It is basically stuck, like glued, TIGHT. It is like it is super glued. I’ post a picture when someone replays.
Then you aren’t pushing hard enough. put the pencil erasure side on a table or counter. Then put the bearing on the pencil. Now push. this will keep you from pushing the bearing onto the table and not out of the stack.