Believe it or not, insects have a knack for working their way into certain locks and building nests or causing other sorts of damage. Not many ways to prevent it from happening aside from properly lubricating and checking to see proper functionality of the locks. Baldwin locksets with exterior thumb presses are particularly prone to mud wasps her in Michigan. They climb in the opening underneath the thumb press, pack it full of mud and dirt and lay their eggs. When the thumb press is pushed down, it often seizes up, and the return spring breaks. This is a problem we have reported to Baldwin, and they generally will send the parts for repair free of charge.