Quick take
Check for a salt bridge first, then verify that regeneration is actually occurring and the brine draw stage works.
Salt bridge
A hard crust can form above an empty cavity in the brine tank, making the tank look full while no salt reaches the water below.
No brine draw
A clogged injector, restricted brine line or valve problem can prevent brine from being pulled through the resin during regeneration.
Regeneration settings
Demand-based systems may regenerate less often than an owner expects. Confirm hardness setting, reserve capacity, meter operation and actual water use.
When replacement makes sense
If the control valve is failing or resin is badly fouled, repair cost can approach the value of a newer high-efficiency system from RKIN, SpringWell or Kind Water.