Confirmed but Leitz converted any early ones sent for works service for free in UK for an interval, at option, don't know what they would do today...**The early 21 & 28's are not milled to prevent the arm to rise. Only the later lenses.
"If you make a mistake you will be sorry! You need the instruction manual
Because you're in Chicago You might want to check with Stan Tamarkin in the loop. He's got an excellent reputation for both price and customer service.
So only original ones are a problem.
If you have a M5 you need to be cautious. Ditto CL!
Especially with LTM lenses like the SA!
Just as annoying (but different) with LTM lenses and LTM Canon bodies.
Don't hand your M5 to another M user...