yes it takes quite a bit of effort to turn it, don't worry it won't break. Make sure you push it in enough to flex it a bit. Then give it a good hard turn. I'm pretty sure it was counterclockwise for me but I could be wrong.
WD40 won't help much, it's plastic. (not metal). Once you've done it a few times you get to understand how much effort is required.
Oh and don't use your finger tips to turn it, cup it between your thumb and index finger with both hands, found that worked better.
Had to replace mine a few weeks ago too, also found it very tough at first.