This isn't funny now.

Ordered rear rotors from dealer. Tried to install. Same issue. Once rotor retaining screw is tightened, wheel won't turn. Confirmed this with both sides.

Also removed the parking brake shoes entirely. Made no difference.

Interference is not with the parking brake shoes, its with the backing plate. All the rotors have a pronounced lip around the perimeter of the inside rim of the hat. That isn't fitting properly into the groove around the inside of the backing plate. That's all we can see.

Rotors Mercedes sold me are 210 423 05 12 64. I have looked online and with the exception of the 64 tacked on the end, that seems to be the correct number.

My mechanic used to own this car. He did the brakes once while he had it, with Zimmerman. He then sold it to a customer about four or five years ago. That guy did the brakes 18 months ago with cheapo white box parts. Never was there any fitment issue, either time.

I have now tried Zimmerman, white box and dealer rotors. While we confirmed with the supplier that the Zimm rotors she was sent were a 'crossover' part number, my mechanic's partner measured then against the Mercedes ones and says they are absolutely identical in every dimension except that the hat on the dealer ones is a hair larger diameter.

The old rotors, in other words the ones that fit, are a hair shallower if you measure their height. Luckily they are still functional, just warped.