What is there at the fitting to renew? Once the cartridge, the valve should not close tightly.
And the O-ring seal, should emerge once water not only from the outlet.
But here you get even after more than 10 years still spare parts from your installer.
The installation is very simple. Place the O-ring under the faucet and then all the tubes stuck through the tap hole. From below the connecting hoses stuck through the flat seal and then hold this up to the worktop. Place the semicircular Unterlegschreibe onto the threaded rod and the nut loosely tighten. Check the the lever can be rotated equally to left and right, then tighten the nut with a wrench Basin with 13mm intake. If the valve is mounted on a stainless steel sink the white reinforcing plate necessarily installed. Then tighten the union nuts on the angle valves with a 19 mm wrench, thereby securing twist with a small pump pliers against the hoses.
I was allowed / had this faucet installed at my home the same and it looks really classy and slim from. You never learn from, knew to just not what an aerator. Should this be clogged, it sometimes helps to clean this in a vinegar solution. Alternatively, I build them like a new aerator one, this I always lie ready to hand in my company car.