The dampers are under the black plastic housing on the print head... BUT I'd try the capping station first:
There are two tubes coming out of the bottom of the capping station and they go into the drain cup that feeds into the waste bottle.
Pull those tubes out of the drain cup, and pull from each one (while pinching off the other)
No suction at all (hard to pull syringe plunger) means the line is BLOCKED. You can clean it out with cleaning solution.
Easy to pull, but just get air... no ink. This means there is no seal between the cap & the head, or there is a crack in a line somewhere that is breaking the vacuum.
Pulls ink... this is how it should work. If it pulls ink from the capping station then you may have a bad damper, a bad inkline between the head and the subtanks/cartridges, or even a bad head.