Don't "tighten" them!
They need to be somewhat slack in the grips so they can fold when (not if) they hit something!
The centrifugal force of rotation will move the blades into the proper position when powered up.
And try this...
http://www.dream-models.com/eco/index.html
And all about how and what to fix:
http://bladecprepair.com/index.html