...kataignu are dirt simple. I got mine put together in less time than it took to cut the hakama.
Well, maybe not less time, but still not much time.
I fixed the shredder.
Or rather, I disassembled the shredder and put it back together, after which the auto-on/off started working again (and shutting off the shredder when there was no paper in it). No idea why it wasn't working. No broken wires, no stuff stuck in the beam.