Electrical problem with clocks

[Val]

Looks to me like nasty wire breaking somewhere in the wiring loom. First try with industrial amount Halfords electircal contacts cleaner to clean the connector that goes in the clocks.

Here is how to isolate and find out where is the fault:

You can replace the power supplied from the loom wires to the clocks connector - R/G red gray wire 12V positive the B black wire ground. You can replace both with direct wires from other place to supply power. If after that clocks work fine all the time that means the problem is somewhere in the wires in the wiring loom. If the fault stays the same means the problem is in the clocks. You can get them to some electronics guy to try to find and fix the fault.