My goodness you both are a wealth of information. You ought to start your own sales yard for toy motorhomes. Oh yea they don't make them anymore. I cleaned the contacts on the panel and that seems to have helped greatly. Now my black tank goes to full read at 8 gallons while my grey reads full at 6 gallons. There are no "pots" to adjust on the panel that i can see ( I removed the panel and examined it). I continued to add water and the black took 14 gallons, but the grey was overflowing into the shower tub at 8 gallons as I put water in at the sink. Any thoughts on this?