I installed s brand new UL40 last summer. The unit has been generating a little bit of chlorine 24/7 since then. About a month ago the cell maintenance light started flashing. When I remove the cell, I don't see any build-up (see attached pictures). Still I feel like I have tried everything to clean the cell with water (waterpick, garden hose), but the light is still flashing. Does this mean it is time to soak the cel in some chemicals?