If your clock has stopped working and you think it is “wound too tight”, DON’T TRY TO UNWIND IT! You will just break it worse.
I just received a Schatz 400 day anniversary clock that was made in April 1953. Someone pushed on the “click” (the device that clicks as you wind the mainspring). It unwound with a big bang, and damaged the barrel and broke one of the pivots (the small ends of the gear shafts. This added at least $70 to the repair bill!
In most cases, your clock did not stop because it was “wound too tight.” It stopped because it needs to be taken apart, cleaned, and other necessary repairs made.
DO NOT TRY TO UNWIND YOUR CLOCK! BEING “WOUND TOO TIGHT” IS NOT THE PROBLEM.