That certainly was an interesting thread on the clock TonyS.
I have been told that on some printed circuits small diodes break free from their solder bases and through that everything seems to stop working. A good few years ago in my modern the heater back light failed. £525 from Renault to replace the heater display

I found out through a contact that all it was, was a solder joint come unstuck, I removed the heater display panel and located the solder joint and just dropped some more hot solder onto the spot, and hey presto light worked for ever more
This was such an achievement for me especially with my auto electrical record!!!