Did you get the cap open?
Remove the cap from the tank (two screws, once open), disassemble, and buff the sliding parts with a fine SS wire brush. Lightly grease, re-assemble. This will last for ?? miles/years before you need to do it again.
The key lock part can be a pain. Liberal dose of 'fish oil' then work the action on the bench a few times. Repeat.
Rick
