It sure seems like any debris large enough to clog a line would have been captured in the cooler before hand. Is it possible that your line is bent?Ok my plan is to replace the aux cooler with a 6.0 cooler. Before connecting all the new stuff up I plan on taking the existing lines off. Push some weed wacker string all the way through the existing lines and connecting the weed wacker string to a drill. Spin it around a bunch of times and see what comes out. If I can't get the string through I know I have a clogged line. What do you think? Is there a better method for cleaning out the existing lines?