Fixing a Toy Pull String sound box

Sorry to hear your lovely toy is not working properly, I too had same issue with a “Santa” that we have had for many years until my youngest grandson pulled the string too far, we took it all apart and found that the wheel that held the drawstring had broken at the base, after much playing around with it and a lot of research finally gave up and bought a new mechanism, good luck, hope you find another way rather than buying a new one, (the fact that we are here in fixit tells me we are the kind of person that would rather repair it than get a new one)