Update...

As I mentioned yesterday, I increased the SWCG to 65%. I tested again this evening and the CL level increased by .5 ppm. So the cell is working, although I'm having to set it at a higher level than when it was new. I turned it down slightly to 63% to see if CL levels off.

I know the manual says only to acid wash if scaling is severe, but I'm wondering if an acid wash might help it work more efficiently? I did find one post where their salt reading was incorrectly low and an acid wash corrected the issue. I've never acid washed it before (again, it was installed in June 2008). Might I harm the cell or shorten its life by doing an acid wash?