YES it works, and beats paying someone to restring an instrument.
This is handy tool that saves a lot of time and aggravation when putting on new strings - you can skip all that slow turning pegs by hand and just wind away!
I picked this up as an impulse purchase, but I'm going to buy a few more and give them to other dulcimer playing friends. I wasn't expecting it to make changing strings so much easier.
The string winder is interesting. Wasn't sure about it but reviews were good and it was cheap. What can I say. Actually, it is a great aid in putting on new strings. Will see how long the plastic lasts but it's first use has been successful and definitely reduces the time necessary to change a set of strings.
I wasn't sure that string winder would work when I first got it. The part that goes over the peg seemed really loose. But it still worked fine and made changing my strings a snap! (That is - once I got a neighbor to help the pin end for me.)