I've updated the post to specify that it's a Pro. The issue is that one is missing the adjustment screw hbsp25 and piston hbsp21. The other caps seen better days but I'm hoping the worst of it will polish out.
I would check out the Hope diagrams on their website.
The little alloy plunger, that sits in the cap and the thumbscrew moves comes in 2 thicknesses. No idea if it would effect anything really, but when there are two of something it always peaks my interest.