can test this by grounding the green w/black stripe wire on the vtc solenoid which is on the other end of the cam near the firewall. Leave the solenoid plugged in when you ground it and if the noise stops its the vtc gear for sure. You can also turn them on with conzult or blazt computer software. I don't think you can just replace the spring behind the front cover. The vtc gear has an internal spring too and I'm pretty sure you are gonna have to replace the whole gear to fix the problem.