If you have the plastic rear wiper arm, then the plastic is warped. Now, BMW does not make that plastic wiper arm anymore, you would need to get the metal wiper arm and a new wiper blade (because the plastic one connects differently than the metal one).

I would recommend getting a new metal arm and add the Bosch ICONS 418A or 418B or Valeo Ultimate wiper 18" size at Tirerack.com

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