I have a mint Remington 581 that when you close the bolt the trigger
isn't cocked. You can push forward on the trigger & it will engage.
Is there an easy fix ? Looks like you could push out that lower pin
& maybe stretch the spring slightly ?
Agreed, replace the spring if it needs a new spring. The insides of the trigger housing might also be gunked up, disassembly and a good scrub might do the trick.