Craig, try doing the muriatic acid treatment as outlined in your Owner's Manual. After finishing that, put 1/2 lb. granulated table salt into a 2 liter soda pop bottle and fill it the rest of the way with hot water. Shake it up, to dissolve the salt in the water.
Then pour it in the toilet and flush the toilet. If the Lectra/San now works correctly, the electrodes were just dirty. If it still alternates between the yellow and green, it's telling you the electrodes are on their way out and will soon need to be replaced.
If that should be the case, just keep using it until they're gone the rest of the way and it starts short-cycling and lighting the red blinking light. At that point, the electrodes are completely shot and have to be replaced.
Normal electrode pack life is 3-5 years for a weekend boater, less for a liveaboard.
