Hardkey not working very well

This will either be the keycap rubbing against something or wear in the key mechanism.

If it's the keycap:

First pull it off and re-fit it as it might not be fully straight and seated.
If it's still touching, figure out where (maybe use some paper as a feeler gauge) and gently trim/file away the offending plastic.

If it's the key mechanism then it's best to replace the key.

Your local ETC dealer can supply a replacement key, and they'll be able to fit it for you if you would prefer.

- On Eos Ti and Gio you'll need to pull the plunger out and fit it to the keycap before refitting the cap, otherwise it'll sit a bit higher than the other keys.