Often we are faced with a well used rod that has ferrules that are sticking. Most people take some steel wool or worse and rub the male slide. I know, rubbing the male slide is not a bad thing but for God's sake DO NOT USE ANTYHING abrasive.
When the rod left the factory it probably had a good fit so what has happened? It is doubtful that someone broke in to your house and added metal to the male slide so why remove any? The first culprit is oxidation, you know, the crud on your Mom's silverware, over time this builds up and needs to be cleaned. Often forgotten is the female slide, whatever oxidation on the male is sure to exist in the female slide so it needs to be cleaned too. Careful use of cleaners and extra careful use of acetone can clean out the female slide. All that black junk on the Q-tip was hampering the fit as well. Another thing to look at is the end of the male slide, has it been dropped and mushroomed making it hard to insert, Use a micrometer check to that the slide has a uniform diameter. Additionally the female slide may have been hit and dented and is reducing the inner diameter. Perhaps some water has snuck in and caused the bamboo to swell increasing the diameter of the male slide particularly in hot and humid environments.
The botton line is sandpaper and other abrasives are a LAST resort in tuning up up a poorly fitting ferrule union on a rod that has been fished for a while. Get out the tweed hat and the Sheppard's crook pipe and go Sherlock Holmes on that ferrule, leave the sandpaper in the drawer.