can't understand inconsistent readings

[KNIGHTCAP]

I have a Goldline Aquarite SWG, T-15 cell. I am getting very inconsistent readings on the display. It says the salt level is 2200, then it will say 3500 the next day. This is instant and average. The display keeps toggling back to metric, and the cell to T-5, then I use the Supercholrinate button to fix both; the next day, its changed again on its own. My chlorine level dropped to almost 0.

I tried removing the display, then re-seating it.
I brought the water to a local pool store (I know, I know...) and they tested it as 4000ppm salt. Brought it back 2 days later, again they said 4000. Using some type of electric meter. I don't have a salt meter or salt test kit.
My display currently has an average reading of 2200, and the Check Salt light is on (not High Salt)
Yesterday, the LCD display (where it usually has average) was saying Hi. I've never seen this before.

My plan:
1. clean the cell in muratic acid
2. take the cell to Leslie's and test it
3. drain some water and re-add fresh water
4. remove the display again, clean the contact points with alcohol.

Other option are buy a new display, and buy a new cell. Does anyone have any ideas of why everything is so inconsistent? Can a high salt level (if really 4000) cause the display to go haywire?

 

[JVTrain]

Sounds like a good plan. What is your current water temp? Temperature can affect the accuracy and consistency of salt readings, but it would typically read low in cold water, normal in warm water greater than 70 degrees or so.

 

[KNIGHTCAP]

water temp is around 71-72. I brought the cell to Leslies, they hooked it up to their machine and said FAIL.
1. anyone have experience with Leslies - do they all "fail", in order to sell more?
2. would a bad cell lead to these types of inconsistent readings of salt level?
3. any preferred place to buy these? Leslie's is 689, I see on the internet at 489 at Amazon.