1989 190E 2.6 170,000 + miles original

I am looking into changing the timing chain and all components involved;

I have no reason to, except;

Some Mercedes "people" have said I should to prevent the worse problem.

Also a friend's 190e 2.6 chain just broke !

1. When I get the cover(s) off can I measure to determine if I really need to change ?

2. Or more to the point to see how much wear, if I was border line and so forth ?

Bill