Lectrasand problem

[CW]

I have had my lectrasand for six or seven years and it has only worked properly for two or three weeks in a row. When you flush the cycle starts but a couple of seconds after the macerating cycle ends and the treatment cycle starts the system stops and I get a slow LED that says incomplete treatment. I have changed plates twice and it will work fine for a few days and then stop working. I have cleaned it with acid as directed and some times that will make it work for a day or two. I have check the voltage and even installed a large deep cycle battery two foot away. No help. I sure would like so advice