If you replace the chain only you are still at risk, because the part is still briddle and can break (it has happened, according to a Mercedes shop here in the Washington, D.C. area)
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Most MB mechanics will tell you that 95% of the time the problem is the guide rails not the chain. It is very common for the plastic to break and get jammed in the chain....and then you are in for big time $$$$ to fix. So replace the chain AND the guide rails. I had mine done about two years ago for under $800 at an indie shop. The rule of thumb on chain and guide replacement is 100K miles and/or 10 years. The plastic pieces are bright white when new. As they age they become a brownish/yellowish color. If you do an inspection and find a loose, sloppy chain and/or off-color plastic it is time to do the update.

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1986 560 SEL (159K miles)