The salt generator will not function if your PH is not in the specific range that it needs to be in. This information will be in the owners manual for the salt generator. If you do not have the manual you should try to get one off the manufacturers website - or better yet call them directly.
The salt generator cells need to be changed periodically as part of routing maintenance. Since your model is old, most professionals will have trouble servicing it. Try to get as much information out of the manufacturer as possible.
I hope this information is helpful