[sammyg2]

Harmonic balancers are designed to dampen vibration at critical speeds.
i.e. every piece of rotating equipment has a critical speed where the natural resonance of the rotating parts matches an excitation force, a certain running speed.
In other words it's like ringing a bell. A bell rings at a certain frequency, and when an external vibration is at the same frequency they will amplify one another significantly. That vibration can become severe enough to damage the machine. A harmonic dampener is designed to lessen that effect and keep the machine from breaking.
It's not something you should mess around with. A broken and glued one will not dampen as designed.
Get a new one or a good used one and put it on and sleep well.