This is NOT the system where you put your stuff into a physical locker but one where it is trundled away into some mechanised storage area run on the lines of an Amazon warehouse.
The machine misbehaved and I could have missed my train. My receipt ticket was accepted and the process of retrieval began. Then the display screen went BLANK. EEK - this was 29 minutes before the departure of my train to Brussels for a Eurostar connection. I should have taken more notice of the malfunction that earlier had swallowed 3 Euros without issuing a ticket; but at the time this seemed trivial.
Human intervention IS possible but depends on you remembering EXACTLY what time you put your luggage IN and which (unimpressive) machine swallowed your ticket without performing the service you've paid for. A search has to be made of the "used" tickets in the machine's innards (a cardboard box).
I am NEVER going to put a ticket into an automated system again without having photographed it first. So much for German efficiency. I'm not ungrateful for the help of a young Deutsche Bahn official but, in retrospect, can't help wondering if his expertise came from regular practice.
WARNING - on my return to the UK, it was not good news to read that there are proposals to introduce such systems to London. Stuff happens; then it spreads.