Did you ever try to tie a knot in an upper register string that is just the exact length you need only to have it slip through the sound board hole before you can pull it back up and insert it through the tuning pin?
Carl, thank you very much for your reply. I tried to position the clothespin carefully so that it would not pop off and hit the soundboard, and I made every effort to avoid applying any pressure as I tied the knot.
Rosalind- Something else just occurred to me. You could also start the whole process by tying a knot in the string and then threading it down through the hole. The knot will prevent it from going all the way through. When You have tied the knot on the other end of the string, you could then pull the string up and untie the first knot.
Check your local $ stores- I managed to find some small, rubber covered clothes pins that I use for alot of things- none of which is hanging clothes- LOL.
What a great idea! I wonder whether a tiny piece of masking tape at the very end would also be enough to prevent it from being pulled through the hole.