From elsewhere (not my clock!):
I wonder if anybody would like to have a go at fixing my Karlsson Big Flip clock. I live in central Brixton, and would be happy to pay for a successful repair. I just did some fault-finding.
The calendar mechanism (powered by two D-batteries) works fine - if I rotate the weekday thumb wheel, that activates the day and month mechanisms correctly, and but it seems that the trigger from the analogue clock that activates the day-date mechanism is not working. In the photos you can see the three connecting trigger wires, ending in a white plug, disconnected here for cleaning (and later reconnected), to no avail.
This task may suit someone who is an electrical/electronics hobbyist. If it doesn’t work out, so be it. This is a last attempt before junking it.