I have a 1204 Mutoh and have had the same problem before. The maintenance stations should be the same, or close. I'll tell you what fixed mine. I used a 10cc syringe and tried to push fluid through the 2 pump tubes and just like yours, I could push fluid through only one tube. The other one was plugged badly. So, I used another 10cc syringe, this one was empty and closed, hooked it to the plugged tube that exits the bottom of the pump. I pulled it open and used a short piece of wooden rod to hold the plunger open. Then I used a syringe full of cleaning fluid, hooked it to the top of the plugged tube, and pushed. This way you have force working on both sides of the dried ink that's in the tube. This worked for me. You can buy a new maintenance station on ebay for less than $300. Also, make sure that the air-tube that is connected to the bottom of the cap top is not plugged. My 1204 has been plugged here half a dozen times over the past 2 years. When this air-tube is plugged, the maintenance station will not work right. Good luck and welcome to the Ink-on-the-Fingers Club.