Ever tried to push a cooked noodle up a straw?  That's what trying to feed a pickup lead or other wire through a blind channel in a guitar can seem like.  Well, unless you are building from scratch, there's a good chance somebody already pushed the noodle for you once so take advantage of that by planning ahead.

When you remove pickup leads or other wires, tape or tie a small piece of string to them as you pull them out of the body.  Tape off the string at each end.  Now, when you are ready to reinstall the component you don't have to push that wire back through the channel – you just attach it to the string and pull the string back the other way!

In this case I used some of the wife's fancy shiny purple craft cord, thinking it would show up better in the pictures.  You can use any string that won't break easily.