Otto Bock Start M1 Intro Service Manual page 13

Now you can also pull off the swivel segment and put
down the parts as shown in the photo.
Pay attention to the clamp piece, which is only
laid in.
2
For reassembly, please proceed in reverse order.
Before putting the parts together, lay the clamp piece
into the opening of the frame tube as shown in the
photo.
Use new set screws coated with thread lock.