Watermaid Cathode. When does it need replacing?

I have been running a Watermaid Ezy-clean cell for about 10 years now. The anode has darkened in color and there is a little pitting near the seam on the cell. It still seems to work OK but I am wondering at what point should I replace it? Does anyone have any experience with how long these last? I see they are about $150 from an Australian vendor.

dave.

Nobody has experience with replacing a watermaid cathode?