Do you mean say a wall clock?
Its the main spring?
It is not warped or powerless?
In 1972 and 73 I helped out at my mother optical laboratory, where there was a jeweler, an watchmaker and a trainee, the watchman repair was friendly and I keep watch him fix the watches, he was very experienced and had a amazing skill with those minuscule parts.
The brands that most often came up for repair were Technos, Mondaine and Orient (which still exists), followed by Citizen, one day showed up an vintage Omega. Women's watches had incredibly small mechanisms and was difficult to see the parts. He used a small magnifying glass in his right eye during disassembly and subsequent assembly.
He cleaned all the mechanism with benzine prior to assembly, some clocks were left to soak in benzine until the next day for some reason.
Hope this help:
https://relogiosmecanicos.com.br/curiosidades/o-escapamento-de-ancora/
