Every 3 months you gotta clean tubes and dampers. If a damper is bad then change it. If you dont want to risk it just change dampers every time you open for tube cleaning.
The way i do, unscrew damper assembly, get hose to a container then push hot water from where you put catridges. I push water until i see clean water comes out of the other side.
Then open damper assembly change dampers and clean damper adapter with hot water again.
If you wanna clean dampers, push your fingers to circles then push water with syringe. Do this until they are clean, if they leak or if you see particles that dont go, replace them.
also check catridges, if they dont give ink flow well clear or replace them. Do these at the same time.