This unit is critical to the operation of your softener. It is used to bring the brine into the tank that cleans the bee bees of hard water deposits. It is therefore just as critical to keep this unit CLEAN. It's natural tendency is to become contaminated by hard water and cease functioning. The owner's manual has a great section on this unit and how to take it apart and how to reassemble. Low water pressure at the inlet to this unit will also degrade its performance, so if you have a water filter prior to the softener, make sure it allows adequate flow.
BTW, there is nothing inside of this unit that will wear out. However, some of the parts are tiny and ez to lose track of; hence my need to reorder this whole thing which gives me replacement parts for the whole unit. Also, found this on amazon for 10 dollars cheaper after I had ordered...my bad.