chlormatic III chlorine generation problem

My pool is 3-4 years old and I had the Clormatic III, CM301, installed at time of construction. It's been great but I'm now experiencing an unusual problem. I noticed chlorine levels getting very low. There were no fault indications on the Clormatic unit. Checked the cell and it did not appear to have any buildup. Had water tested at local pool supplies store and the stabilizer was good. Salinity level is 3.4.

When I began paying a little more attention to the lights on the unit I realized no lights were on (Cell on, Flow, Cell Resting or Cell Reversing). I cycled power to see what would happen and when I turned unit back on (after about 15-20 seconds) the Cell Reversing light illuminated. Checked again in about an hour and the Flow and Cell On lights were on also. Let pump run for 24 hours and chlorine levels were up the next day. After a couple more days I noticed the same problems. Chlorine almost nil and no lights on the Clormatic unit. Recycling seemed to work again for a day or so. Now, as I watch the lights, the Cell Reversing stays on quiet a bit and the Cell On and Flow will illuminate for short periods (30-45 seconds at a time).

When the unit calls for Cell On it seems to generate chlorine but the cell will not stay on enough to keep pool chlorine levels up. I have the unit set on 90% and the pump is running 10-12 hours daily. I either was never given an owners manual by the builder or I have misplaced it. Is there any way for me to get one? I tried a Google search online but didn't have any luck.

Any suggestions? It sounds to me like a controller circuit board or something, which will probably require a service guy to come out. I'm not sure how the unit is set up since I haven't looked inside and I don't have a schematic. Just wanted to make sure there wasn't something simple I was overlooking. Appreciate any help you could offer.