So I was given a 16S South Bend grade 317 to get back into "working" condition from an old friend who found it in a drawer with some of his other small vintage trinkets. The watch appears pretty clean, but upon receipt the mainspring was fully wound and the the balance wheel was "overbanked", if I'm using this term correctly? So now I have to wonder how long this pocketwatch has been fully wound, and knowing this person who has been collecting for many years, it could have been sitting like this for many years. I tried doing a search in this repair forum for "set mainsprings" without really finding too much prior discussion. I have seen where many repair people will automatically replace the mainspring when doing a routine cleaning? So I guess I'm asking if there is any type of instrument or tool to test the "strength" of the current mainspring, to see if it really has lost any of its "power" so to speak? And when a mainspring is considered "Set", what does this really mean? Thanks in Advance for your comments, opinions, and/or knowledge. Brad Maisto, Indiana Chapter 18 President P.S. This is the same friend who sold me a South Bend "294" in a solid 14K yellow gold hunter case that needed a dial. Good thing dials are interchangeable from watch to watch !