i haven't been able to easily clip in with my new clipless pedals.
i bought some on ebay a while ago and they sent me the wrong ones. there were the light action model. i clipped in those without a problem. i noticed the cleat spring in the zero is much more snug compared to the light action. the spring is oiled properly, i think.
i read that the cleat spring is supposed to move freely. but the new cleats i have now, the spring clip is very snug. i don't know if it's too snug or what.
should i try to pull the thing apart and loosen it up?
You should center the cleat on the pedal with your foot. You'll know when it's there. Then put weight on it and twist your foot back and forth like you are putting out a cigarette. Once you get the motion, you'll remember. It took me a while to get it, too. It takes everyone a while to get the motion right. After that it's simple.
Your 4 plate screws might be too tight. they should be snug, but not tight-as-you-can-get tight.