It is a common myth that you can over-wind a clock. If your clock has stopped moving, it’s likely that your mainspring has become worn, dirty and/or dried up. This causes friction and makes it difficult or impossible for it to release power within the clock movement. Once your clock has been serviced or overhauled, you will be able to wind your clock without any problems. If you mainspring actually breaks, that is not your fault, but simply the result of a worn mainspring.