What Thermodude says is correct, but being a novice I'd leave it to the professionals. One other little hint is that when you replace the screw us a little bowstring wax on the underside of the head. May as well do them all while you're at it. Many times the screws aren't tightened as tight as you might think. Just that aluminum and steel don't mate very well and gall (spelling) together. The string wax will help prevent this.
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