As the subject suggest my Idler pulley seems to be making a rattling/screaching type noise. Me and my friends listened for the noise and its not coming from the alternator, so that is out of the question. If this an easy fix, simply by replacing it with a new pulley?, If so How much is the Idler pulley? I would like to get this fixed ASAP, it is very annoying to listen to?

Thanks in advance!