One exhibit is turned by hand at the platter — the only way to hear how it sounds.
The spring snapped, and there is nothing to replace it with: the size is non-standard. In everything else the machine still works.
To demonstrate the sound, the platter is spun by hand and released. The speed falls and the pitch drifts downward — which is exactly how visitors hear what "the spring has run out" means. Koval says it explains the mechanics better than any label.
