Replace if there is a leak at the base of the spout and/or the spout is difficult to swivel.
4050 s4050 ring o-ring
Ordered replacement O-rings, retaining ring & seat. Removal & installation was easy, instructions clear.
It was magic! After ordering the spout retainer, O-ring and seat the faucet magically quit leaking without us ever changing anything. I will definitely keep the parts and I'm sure the faucet will never leak again.
K4050 Spout Retainer, O-rings and Seat