I am just starting to trouble shoot this problem. They have not worked since I bought the boat, many moons ago.
I suspect worn out senders. I provided a picture of the top of the sender on the starboard side. Can anyone tell me what kind of sender this is? I don't see a name or number.

Duh! I've got work to do to stop the rusting on top of these tanks. Don't want to have to replace them
I think the only place they are rusting - outside - is at the top near the input hoses, but someday I need to scope the inside to verify same.
I suspect worn out senders. I provided a picture of the top of the sender on the starboard side. Can anyone tell me what kind of sender this is? I don't see a name or number.

Duh! I've got work to do to stop the rusting on top of these tanks. Don't want to have to replace them