[C38] water tank gauge

[David Stoltz]

Hi all,
I have a question about the fresh water gauge on my boat. It stopped working some time ago and I just got around to having a look at it. When I removed it I expected to see electrical wires attached, but all there is is a very small tub that slides on to a fitting in the center of the gauge. Does this sound familiar to anyone? There does not seem to be any type of power source, so is this what signals the gauge as to how much water is in the tank? There is water in the tank now, but nothing came out of the tube when I disconnected it. I blew on it thinking it might be clogged, but it's not. I don't know if this is an after-market install, or if it's factory. As always, any help would be greatly appreciated.
Thanks,
David
Andiamo #297
MdR, CA