BMW 318 TDS

The fuel tank indicator does not mark well. Sometimes it is marking full, sometimes half a deposit and sometimes marking the reservation, regardless of how the deposit is (I now guide me by the accounting). I have been told that first of all do the instrument cluster test ...
Anyway, I am lost and I would like to have information about whether I have or not to change the aforerator, one or both, if it is the problem of the instrument picture ...
it is a BMW 318 TDS of the year 95

Good, what you have bad is the aforerator.
It is located under the rear seat chair on the right side.
The normal thing is that the connections have deteriorated (very common failure in these models).
Take it out and check.