If that doesn't work for you, try this:

Go to Ace Hardware, buy a short length of transparent surgical tubing, maybe a couple feet.

Tape about 6" of tubing into your vacuum cleaner extension, and put the tubing into the servo opening or the center opening.

Don't tape up/ seal up the opening around the surgical tubing, you could collapse the wing.

Stand the wing up so the tubing is down, the other opening is up.

Put a thread (not a string, a sewing thread) in the opening, turn on the vacuum and let the vacuum pull the thread to the surgical tubing. You'll see it in the tubing when it gets there. Along the way, you'll fish the thread up & down, and feel it pulled toward the other end.

When you have thread out both openings, attach a string, pull it through, and with the string, pull the servo lead through.

Repeat as necessary. Works almost as well as the string & weight sytem, sometimes better.

Good luck!
Dave Olson