ktmracing16

My fuel gauge needle never reads correctly. It will read differently every time I turn the key on. If I just turn the key to the on position, I can watch the needle move around, sometimes a little or alot ! I have changed the sending unit in the tank and checked the connector under the drivers door and disconnected the battery and cleaned the terminals. Still the same thing. My low fuel indicator was working but has recently quit. Could it be the gauge cluster ? Any ideas ? How can I test the gauge or the cluster ? Thx, Terry