Yeah, you can undo the screws and remove the cover, this will give you access to the piston, it's probably a combo of carbon and dust/dirt making them sticky. I know mine were very dirty when I stripped them down. When you have the cover off you'll be able to see the needle better and check it's straight, just dont knock the needle and it'll be fine. There'll be no changes to the settings.
Also you can use ATF as oil in the dash pots