I've got this pen and unfortunately I don't know how to restore it. I assume it a leverless of some description.

First off are these pens pull section or screw?

I tried unscrewing it and I hear a crunchy noise I assume from the sac maybe pressure bar. Do force it past this point or is there a different method. I'd rather restore it myself then pay someone else to do it. Any guidance would be appreciated.

DSC_3195.JPG