I have seen 2 with bent up valve train issues. I purchased one of those (as junk) for a rebuilder, finished it about a year ago.

On newer 119s these plastic pieces lift right out after you remove some of the cam journals etc. The tensioner is always a pain, but it should be done. It's not that the spring loses elasticity, but more like wear around the chain face that turns into other [big] issues. 30k mile oil will do it nicely.

It's almost always neglect, like Pat said. For those just getting into the now-affordable 90's S-classes, remember "The 140 is the most unforgiving machine on the planet of neglect and ignorance"