IF it’s the original pin then I’m not sure how you do it with a paper clip. The pin is a sprung loaded pin that telescopes to shorten and then comes out. Getting it back is easy – and obvious when you see it. The pin has a small diameter at the end and a small flat blade screwdriver in the ridge where it gets bigger will close it. this is usually hidden by the strap.
The pin press is for removing bracelet pins so little help I fear. Good Luck. Noel.