Harry Stottle wrote:
.... snipped
It could be that the first guess for a repair is the PCB, then when this is
replaced and is found to have not cured the problem, the real culprit is
detected and replaced, i.e. the fan.

.... snipped

When BG came to fix my Glowworm (according to Wife) they had a device
that could interrogate the PCB so I assume there's a standard interface
that allows them to read fault history and parameters before replacing.

Dave