"Overwinding" is usually a misnomer.
When a clock is fully wound and doesn't run, by far the most likely problem is that the oils in the movement and the grease in the spring have dried out and become gummy. Gears must be able to spin freely in their bearings, and springs must be able to slip against themselves in order to expand from a fully wound state. The remedy is simple. Take it to a qualified repairperson and have the movement overhauled.
If you know that your clock has been serviced recently, then some other issue is causing a problem. It could be a bent gear tooth or pivot, it could be that a strike mechanism is hung up. You will have to take it to your repairperson for analysis and service.
Prestige Clock Repair
Bluff Heights (near 4th and Junipero)
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