I've been getting an intermittent metallic noise from the upper cylinder area which I have assumed is a worn cam chain or tensioner. I removed the tensioner (against my better judgement) which appears to be OK. However I'm not sure about the procedure for replacement. There are no ratchets or 'clicks' as I have read concerning other bikes. It simply screws into the main fitting and then onto the bike. Do I then have to release the screw at the back to allow the tensioner to opperate?