Sal, the external salt tests are for your sanity but ultimately the cell won't work if it can't read the salt
The cell may just have scale build up, so powering down the system, rinsing it off, and if there's scale, cleaning it in a diluted solution of MA and water may be in order (see aquarite instructions for same.)
Once the cell is cleaned, if you still have problems, then it may suggest a problem with the board, in which case you're under warranty.
If after cleaning you still think its the cell, you can take it to an authorized Hayward dealer for a check. The cell will hav a 3 year warranty, so that too should be covered.
If you want to run your system with the cell removed, there's a "dummy" straight pipe replacement you can buy (eg I got one from Inyopool.com) for about $40 - some folks use this in winter to save cell, but I got it just so I could run the system if I ever need to remve cell and send off.
Hope that helps. Just know that the system reads low when the cell is fouled or when the board is having problems. Don't add salt unless you actually need to