During my recent stay in Germany a friend of mine gave me 3 pens he had no use for. I've never heard of any of them and I wonder if I should (or can) fix them. The first pen is "HARO" branded and uses a "Dauerfeder" nib. It uses an integrated piston converter.The second lacks any branding, and lacks any filling system I could see. The third has a broken nib, has no branding and has a piston filling system. Any info you could have on any of these pens is greatly appreciated.