Ok Mel….it looks like the voltage applied to the relay to change it over night be dropping as the relay changes over….a poke about with your test meter might prove this …..then it may be a matter of looking for the reason for the voltage dropping.
perhaps a short or something ?drawing too much current in the TX . May need you to disconnect the Power rail at various points to isolate that which has failed or is drawing too much current.
long distance fault finding is not easy! Hope that has given you some ideas.
顿补惫别…骋4顿础齿
