Hi Laurie,
I've been around the pool industry for almost my entire life. These are just a few things I've picked up along the way:
-Salt cells tend to last anywhere from 4-5 years (From what you mentioned, it seems like it might be time to replace that one unfortunately)
-Never trust the reading given by the salt system
-No need for an overly expensive test kit like the k-2006 (Most pool professionals don't use these kits and I don't either)
As far as your chemicals,
-Cyanuric acid is low (should be around the 60-80 range)
-Chlorine level is also low (manually add a gallon or two of chlorine to prevent it from algae blooms and turning green or cloudy)
-pH isn't bad, but your pool is vinyl so no need for acid to be used
Regardless, the cell should be tested.
MOD note: This set of posts were removed from another thread.