if clogged, you first have to determine if its pumps or supply.
first get a syringe hooked up to the pump line that prints yellow. pull the carriage to the side, away from the capping station, and pull a strong vacuum on that pump line. do you feel resistance. there should be none at all.
if so, get a partner to syringe cleaning fluid into the cap while you pull a vacuum on the other side. keep going until the line is clean. if that doesn't do it, get a small wire and feed it up towards the pump. try to free the clog and repeat the vacuum/solution routine. if that doesn't work, take the pump apart a bit and work the clog through the line.
(also keep in mind that many clogs can be directly beneath the cap, right where the tube begins).
on the supply side one way to determine if you have a clog is to remove the damper and pull a strong vacuum. if you don't get a good amount of ink, there might be a clog. also pulling on a vacuum and having the damper stay concaved after the syringe is removed is a sign of resistance in that line. you can also feed a wire way down that ink tube to clear a clog. or simply put and cleaning cart on that line and pull solution through it (damper off).
