There are sections of broken off cable inside each end.
I should have also said to use a variable speed drill. I like braided wire as well as it tends to fray on the end and help with the cleaning. It won't break off as easy as a solid wire. Figure out where the blockage is, tap a little with a hammer, more drill etc. Even a little heat from a propane torch, if that is all you have, and applied to the heat riser near the blockage will help. Heat, tap and slow speed on the drill with the wire. Access to an air supply is nice as well to gauge how well the air is flowing.
To get the wire out you will likely need to drill a hole in the heat riser away from the end to grab on to the wire with needle nose pliers or an awl - something sharp so as to be able to grab onto the wire and hopefully dislodge it. Hopefully you have access to a mig welder or something similar to plug up the hole when done.
Slow and easy will bring success.