I am replacing the head on my 240d. I have put the timing chain back on the cam sprocket exactly how it came off, but the timing marks on the cam do not line up with the marks on the chain and gear from when I removed them. How do I make sure that the engine is timed correctly? What index marks am I looking for on the crank, etc. I have the MB shop manual, but it is not very specific about how to determine TDC on the crank. Thanks, for your help!!!