Here is a possible fix for inaccurate 405 fuel gauges and maybe other models. Mine would not go all the way over to full after filling the tank. I think it was also reading eraticaly as the tank emptied. The cure was to remove the instrument cluster and then the fuel gauge needle. Then sprayed the needle shaft pivots with electrical contact cleaner. Gauge now works accurately and has regained full range of travel. Contact cleaner is available at Dick Smith and similar stores. I used straight cleaner but there is contact cleaner and lubricant available in the same can. For anyone who is interested, the fuel gauge is a moving coil type not thermocuple as in many none european cars. Hope this helps someone else out.