It seems that 61F's Floatless Level Controller electrodes are dirty and sensitivity has dropped. How can I clean them?
Tarnish on the electrodes will cause poor conductivity.
Polish the electrodes with an abrasive such as fine sandpaper.
Use a cloth to wipe off the residue.
The electrodes are stainless steel, so it is also acceptable to use a commercial chemical cleanser, but be sure that the liquid in the container is not affected. If the electrodes are extremely dirty, it may be necessary to replace them.