0000 bits are hard to come by, but you shouldn't need one. Is yours stuck on? Is it stripped at all?

Turns out that you can't edit a comment after five minutes have passed, which is dumb.

IMPORTANT FOR ANYBODY ATTEMPTING THIS FIX: Try to clean the contacts beneath the contact sticker before you do any of these replacements. It will likely fix your issue. Just be careful to realign the sticker correctly, as Andrew posted above.

This guide doesn't mention that if a button is no longer working or needs to be pressed harder to work, that the contacts on the board shown in step 11 need to be replaced, not necessarily the board or the outer buttons themselves. This video shows how to replace the sticker containing the contacts. I plan to do this replacement myself when the replacement comes in. As of today, such a replacement costs about $10, whereas the board is about $15.

Mine were tight as well, make sure you're using JIS and not Philips and you should be fine. Since this is seven years later I hope you've fixed it though!

+1 on this! Didn't need to replace the button at all.