Posted By:
Rhett YeakleyI echo what Paul has said regarding the pin mechanism being the determining factor in whether the value is affected.
With pins such as Cameo Pepsin's a missing pin doesn't mean too much as they are the same size as all the common American Pepsin pinbacks and the pin can easily be replaced by a pin from another series. However, an example of a pinback that would be affected are the extremely tough Stenzel's Rooter Buttons. Example of mechanism below...

As you can see from the scan the pin itself is imbedded into the rim which would be near impossible to replace once missing or broken.
-Rhett