My assessment was correct. The watchmaker called me, the main spring is broken. Besides replacing the broken spring, it needs cleaning and oiling as well. If I don't do it, it does not work anymore. If I do it, the cost can easily buy a working one on ebay. But I will still do it. The logic is simple: If buy another one, it's in unknown status. At least, I know this one's mode. One working PW in hand is better than two broken ones.
This hobby is somewhat troublesome. The subject collectible is too fragile. The initial cost is modest, but as long as it keeps running, it could become a money sink
If put aside without winding,,,,,,, this is not a rare model, nor a precious metal cased model,,,,,, if this one does not run, which one will run