Yes we tried to use parrallel resistors so as to 'scale down' the resistivity of the senders. It is theoretically valid that this analog approach to recalibration would improve the situation.
However you also need to account for the fact that the gauge reads 100% for an unacceptable amount of time. This can be done with a series resistor
Unfortunately as i hinted in my previous post, there are other electrical problems that have to be addressed as well. Therefore this does not work on its own and i recommend that you do not bother.
If you are going to do this regardless i may as well tell you that the gauge reads:
<22 ohms 100% fuel
>66 ohms 0% fuel
You can then calculate the optimal series resistor (probably 16.8ohms and the optimal parallel resistor 140 ohms. see my working attached:
