Oil Gauge is full of oil

Oil Gauge is full of oil

Is the oil gauge on a fa50 supposed to be filled with oil? I took it apart and it looks right but other pics I've seen you can see the E and F and the pointer. You can't on mine because it's full of oil. It still works and the ballast is fine I'm just curious if I'm missing something on the inside of the gauge or something. Thanks all!