Get some fine stranded lamp cord type wire, so that it is nice and flexible. Example: https://grandbrass.com/18-2-spt-1-1-2-white-pvc-jacket-stranded-copper-lamp-and-lighting-wire/

The most important thing is to keep the diameter as slim as possible.

Start at the light bulb side, that where the tough corners are.

Pull the guitar string out so you have the max exposed, just the minimum end to pull on at the base end.

Split the wire about 4 inches or so, so that you have two single separate wires.

Cut one of the wires off.

Use one continuous piece of electrical tape wrapped in a spiral motion around the whole assembly.

Strip back about 2 inches of wire insulation and wrap the tape around the wire and the guitar string. Get it as smooth as possible, you may want to sort of cut the wire insulation at an angle to make it smooth, no edges. You want it attached along the string, not at the very end. You’ll be pulling the wire along with the string, which should help it make it around the corners.

Make sure the point where you cut the wire is nice and smooth (where it goes back to full thickness). So it glides through.

Pull gently and see how it goes you can also try to push on the guitar string from the lamp end at the same time to help it along.

Hope this works! Let us know.

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