If you have not already drilled...Take the advice of the previous posters. You can easily damage the idle port when you drill out the plug associated with this passage. Follow this link to Tom Endy's Tech Article on cleaning the passages without drilling out the plugs.
http://www.santaanitaas.org/wp-conte...assageways.pdf
I hosted a Zenith Carb Rebuilding Clinic last winter for about 20 Club members and we all used this method to clean the passages and we ended up with 20 good carbs.
Good Day!