I've have a previous model for 3 seasons and loved it

... this summer it constantly gives us low salt errors, even though the salt tests between 2500 and 3500. The plates appear to be worn out (they've been soaked in vinegar frequently throughout their life, soaking them now will remove the calcium build up but they appear to be worn out since we cannot get the old unit to run with them in place).
We purchased the new version from Amazon a couple of weeks ago, and it immediately says high salt. Ordered new test strips (Aquacheck) and the salt was actually about 2700. Amazon has sent us another unit and we are returning the 1st one. New unit has a manufacture date just 2 days later than the first and has the same false High Salt error.
Had to use pucks in a floater to keep CL up while out of town for 10 days.... which of course raised the CYA to around 100. After draining 20% of the pool and refilling we tried the new unit with very low salt (still error-ed as high salt), adding salt to 3000ppm and it again errors as high salt.
The titanium plates are the same as from the previous model, amazingly they work flawlessly in the older SWCG unit. But in the new unit they will only give a high salt warning immediately and will not run. We've decided to keep the last unit from amazon and use the plates in the older SWCG since it's actually cheaper than buying replacement plates from Intex (Titanium electrode $63, ECO electrode $39, shipping $25 = $126).
As for PH rising, our fill water is very high in TA so we are normally fighting rising PH until we can get the TA down. After that its usually just a slow creep up on the PH, I just have to add a little dry acid once a week or so.