I don't know how those things can wear out. Some soft parts can and need to be replaced periodically, but the shifter itself, kind of hard to believe. There are bushings in the shifter and linkages that need to be replaced every so often and sometimes it's possible for the linkage to loosen up where it enters the transmission. There are recessed allen bolts where the linkage enters the transmission that can come loose when you have bad bushings at the other end causing stress on the linkage. I think I'd sure get a second opinion.

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Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles