If you look online a bit you can find good explanations and pictures of how they work. There are a few different types. Mine are simple electrical contacts at different levels, and the water is the conductor. They are not adjustable and may just need a good cleaning. I decided to replace mine about a year ago, but I quickly discovered that was NOT going to happen! I didn't have enough room between the frame and the tanks to drill out the old ones and install the different type without dropping my tanks. And THAT was NOT going to happen after researching the procedure.