Re: ferrule question...
I also think a drill is a very bad idea.
I like the cotton swabbing idea. A q-tip would work well. A pipe cleaner also could work to clean out any grit stuck to the inside of the ferrule.
An air duster could also be handy. Stick the straw/tube in past the ferrule itself (so that you're not blowing the crud further into the rod section), blow it, and the pressure should blow any schmutz out the open ferrule.