is this easy fix?

Depends on what it is. Have you checked to see if it is the sender, or the readout? Either way, it isn't too bad. The cluster's batteries are probably on their way out, which causes random stuff to stop working. Alternatively, if it is just the sender, that should take all of 10 min to replace.

how do icheck if its a sender or readout? by testing resistances on the sender?

Depends on what it is. Have you checked to see if it is the sender, or the readout? Either way, it isn't too bad. The cluster's batteries are probably on their way out, which causes random stuff to stop working. Alternatively, if it is just the sender, that should take all of 10 min to replace.

Yep. The resistance values of a working sensor are in the Bently manual, page 160-4.