I used some stainless steel lockwire aka 'safety wire'. You can get it from aircraft parts suppliers relatively cheap for a 10lb spool. I used ~.022" and weaved it around the link arm and ball in alternating directions. Give it a few wraps and toss in some grease for the wire because it will now have friction on the shaft. You can then twist the free ends together to tighten the whole thing up. Cut off the excess and motor on.

You can find safety wire from many sources and you can get it in many sizes. .022, .032, .042, .062 etc. This stuff is gold for certain repairs.

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'05 E320 CDI
'20 GLE 450