A broken screen or failed seal in the upper distributor can allow resin beads to escape into the water supply. A cracked upper distributor also can cause this problem.
Unplug the water softener and shut off the water supply, then remove the valve assembly and inspect the upper distributor components. Replace the screen if it's torn or damaged. Replace the screen seal if it's damaged. Replace the upper distributor if it's cracked.
You'll need to add resin beads to the filter or replace the resin beads after repairing the upper distributor.
These repairs may help solve your water softener problem
Replace the water softener resin beads
As the water flows through the resin tank, resin beads act as magnets to attract and remove the hard water minerals that make the water hard. Resin beads last for about 10 years before losing effectiveness. Replace the resin beads every 10 years or when you notice that the water softener no longer softens water despite preventive maintenance and system troubleshooting.