This is not a new subject, but after searching the archives I found nothing to help.
I cleaned the connections (press in and threaded on back of fuel/temp cluster) several times and even replaced the temp/fuel duo with substitute unit. Both gauges read 145 ohms, so I think they're both good.
When the dash is warm (the dash, not the engine) I can usually make the temp read correctly for at least a few seconds by tapping the dash itself. I am sure it's a bad connection at a connector or a bad board (copper foil parted), but wondered if there is a common failure point before I tore it apart (again for the um-teenth time!).
Through which harness connector does the temp gauge connect? Does the gauge depend upon the nicads at all, or is it independent from these? The rest of the gauges work perfectly (the service board itself was long ago removed from the cluster by a p.o.)