Put new batteries for waste tank level warning light on my manual pump thetford toilet ( never used it before)- level light !!
Light comes on when I lift the float and I can hear the micro switch clicking....but the light is terrible...can only just see the red indicator when the blinds are shut....
My answer is the same as Jeff's as mine has never worked since day one either. It's not an important feature as like Jeff said, you just have to keep an eye on it. I was told a few years ago by someone who did have the light working said it was rather dim so probably that's the way it is anyway.