Any advice on cleaning smears on the inside of a blade with closed tip?

So I got the tip glued on my blade, and was about to put in the blade film when I realized there was dust through the tube. Should have cleaned it first. I tried a dowel with tissue on the end held on by electrical tape to clean it. This just made more dust because I'm an idiot, and got black smudges from the electrical tape inside the blade... I then cleaned it out with soapy water mixed with rubbing alcohol and now there's no dust, but there are still black smudges.

Any ideas? I'm kicking myself right now.

Try using the dowel with a piece of cloth you clean a TV screen with. Tack the cloth to the end of the dowel, staple, hot glue. Then wrap the rest of the cloth around the end of the dowel. Like a ram rod. No guarantee it will work mind you. Done that a few times for dust when putting new diffuser in a blade.
The smudges are the adhesive from the tape, so the cloth should pick those up.
Let me know what happens.

Do you have a cut off piece from the blade? practice on that before messing around on the real thing.
Alcohol is too polar to remove the adhesive, you need a non-polar organic solvent. I use colman white gas (aka lighter fluid or kerosene) to take sticky labels off CD/DVD cases and other plastics. I haven't tried it on polycarb but its fine on abs, pvc, hdpe and pete. If you sized the blade and have a bit left for a blade plug, try marking it with the tape and then try cleaning it to see if the polycarb fogs up or gets tacky, if it does, don't use it. There are other solvents you can try like fingernail polish remover (aka acetone), lacquer thinner, mineral spirits and even gasoline but it think that's too harsh. Use a SMALL amount on a cloth, not paper

Just hacksaw the tip off and start over. Use a file to clean up the shoulder of the tip and re glue it after. Too much work?
Don Mac.

I finally got a pipe/tubing cutter that worked well for cutting the blades and will certainly never look back.