Hi! Godess,

I remember using a little tool I picked up in my old lbs that bascially pushes out the connecting pin between cogs and then pushes it back in to close - I'm sure Performance bike on line will having them - (http://www.performancebike.com/index.html) - actually I just checked and they do - they call them "chain tools" and they're about 6 bucks.

Good luck!
'calla