I'm off next week so I want to start tearing this apart to see exactly what's going on. I'm going to start with the valve covers to check things out. I hope it's upper guides/rails not anything to deep down requiring pulling the front of the engine off. Is there a link to a online repair manual for specifically the timing chain and components on this 420SEL ? I don't have any books and I'm looking for someting to go by. TIA