This morning I could see that the instrument cluster was working and in perfect condition during the 30 min ride to work, all gauges were fine for speed, rmp, ECT and fuel level. Parked the car, turned engine off and retried many times ... no needles moving.
So it must be a loose contact somewhere, pulled out the cluster but did not disconnect the connectors, wiggled, wiggled, wiggled all reachable cables in the cavity behind the steering wheel, nothing changes.
That is very frustrating since I don't know where to look for this elusive failure. I'd rather have a defective part than that.