Pillow Block

The bearing insert has a convex outer race. It turns in the housing. Stick a shaft/punch/whatever through the hole and move the bearing . Some are pretty stiff. If it still won't move, look for a small pin on the outside of the outer race that engages a slot in the housing. Some bearings use this as an anti-rotation device. Align pin with slot, rotate into alignment with shaft/punch.

O.K. the 12mm size matches up with the posting through a news server in Germany. But it *still* feels like a troll.

Just in case it is for real:

Take *two* of the self-aligning pillow blocks, feed the 12mm shaft through them, and bolt them both down to the mounting surface. The bearings will live up to their name by self aligning. But you do need the second bearing to define a unique axis. With just one, it can wobble all over the place, depending on the forces applied to the shaft.

Enjoy, DoN.