Power valve missing spring ***'y ... why?

I got my carb off and cleaned it up, changed the gaskets, new jet sizing and new power valves. When I got it apart, on the secondary side, the power valve was missing the spring assembly. It was just the diaphragm and the threaded stub. The missing pieces were not in the bowl, so someone at some point took them off. Why would someone do that? Am I missing something? I put in a new power valve and it runs beautifully.