There are creaky sounds coming from the dashboard, with the ignition on, before turning the engine. The fuel gage will mostly not rise at all. Sometimes, it rises a little, shakes, and falls back to where it started. Then sometimes, it will rise, but stop randomly, within an interval that matches the volume in the tank. The other gauges seem to work fine.
https://youtu.be/TLlhJJLhl-Y
Some youtube-video suggested heating the panel on an oven. I took it out, and put it on a radiator, at about 85 Celcius, for two hours, and put it back in. No effect. The condensators look fine, and there are no signs of rust anywhere. Not on the contacts either.
This is the model I have: