1983 380 SL
There is no reason not to change the tensioner, in fact you should change the tensioner, I just didn't want you to think that changing the tensioner could solve cam timing mark alignment problems because it won't. When the tensioner goes bad you'll get excessive chain slap and when the chain itself is also bad from excessive wear, the entire problem becomes multiplied and the guides can break and that can lead to catastrophic engine failure.Thanks Jyuma, I was just hoping it could have something to do with it considering the timing chain wasn't fully stretched but i guess I was wrong. Well at least you saved me some unnecessary mounting to test my theory. I'll just change the chain.
If you're going to do the job then do the whole job... chain, guides, tensioner, sprockets (if they are badly worn) and don't forget the oiler tube connectors. Follow PanzerPuffs instructions in his excellent video and you'll get the job done right.