There's been a lot of discussion over time about the aerometric breather tubes, and how to remove them. Most of them are wrong. The method that I'll give below works nearly every time. There are always exceptions of course.
First, you are not going to try to drill out the remains of the breather tube. If you try to drill it out, chances are that you will end up with an oversize hole, and the replacement breathe tube will not stay in the feed. The reason is that to get all of the breather tube out, you have to a] drill exactly on center and b] have to be slightly over size.
You'll need a pin vise and a drill that is slightly larger than the ID of the tube, but smaller than the OD. I'm not specifying the size because it's not critical. It just happens that the one that I use from a bunch of Harbor Freight mini drills is about 0.037" or 0.95 mm.
Using the pin vise to hold the drill, drill by hand into the end of the breather tube. Don't try to drill in all of the way. As a matter of fact, DON'T go all of the way through.
Then heat the end of the feed over your heat gun. When warmed, twist and pull out on the drill and breather tube at the same time. The bit of tube should be stuck to the drill, and will come out of the feed. Heat again to allow the hard rubber to return to shape, allow to cool, and then insert the new breather tube. Use a bit of a twist as you push the new one in place.
Edited by Ron Z, 19 June 2009 - 14:02.