Move the carriage to the left and look to see if the printhead is totally parallel to the platen. I use an automotive feeler gauge to check mine, but a visual inspection should be good enough. If one side of the head is higher than the other, then it can not set correctly on the cap. And the pump can not pull ink through the head. If the head is parallel to the platen, then you might need to remove the cap and the fixture that holds it in place. You would have to take the right-side cover off and move the carriage to the left. There are 2 screws on the right side of the fixture that holds the cap in place. You do not have to remove the complete maintenance station--just the fixture that holds the cap. Make sure that the 2 short tubes under the cap are not plugged. Make sure that the one longer (breather) tube is not plugged. With this fixture off, you have easy access to the 2 tubes on the top of the pump that pull ink into the pump. Use a syringe to push some cleaning fluid into both top-tubes on the pump. Fluid should flow through the pump. If it doesn't, then one or both tubes are plugged.
There is not much free-play (or adjustment) in the maintenance station. I have heard of some people shimming one side, but I think that is rare. When I put a new one on my 1204, before I tighten the 4 screws that hold it in place, I push it as far as it will go to the left. Then, I tighten the 4 screws. Stay with the beast--this stuff is not rocket surgery or brain science.