On our 37 Cruiser (2006) we had the same issue. At the upper end (inside the base) the probes were a bit corroded and there was moisture inside the base. Apparently, the sealant had broken.
I pulled out the probes (if you do it be careful that you do not tear the insulation or cover it with a heat shrinkable tube), sanded the corroded parts on the probes, let the base and the probes dry out, put the probes back and sealed the areas where the probes are inserted into the base. The problem has not occurred again for three years.