is this a manual chain thensioner? and you probably dont have to put the spring in..... BUT when i did i put the spring back in when i put in my Manual chain tensioner from ONE STOP PERFORMANCE they had the parts all refabbed at their shop and sent it out while i was on the phone with them... i dropped 2 teeth on my HC so i needed a manual tensioner.... so far its been the best thing ive done... besides airframes
goodluck hope that helps