Take a piece of string or a fishing line and tie a small weight to the end - like a fishing weight (worm weights work great cause they're bullet shaped).

Drop the weight in at the servo hole and rotate the wing around while looking down the tube the extension comes out. When it's out in the tube stand the wing upright and the string will fall out at the root.

My 4* didn't have any strings and this method took all of about 1 minute to run a new "chase" thru so I could pull the servo leads out.