If the passages are plugged get your self an old speedo cable. Take the end and beat it with a hammer. This will cause speedo cable strand to sticking out. Put the good side in a drill and feed it into the passages. As you are going stop and blow it out and continue.
Add some carb cleaner at times and soak the passage then use the speedo cable again. Have used this hundreds of times. Workers great it's like a plumbing snake for carbon