It will be more easy to just replace the whole arm, buy an arm with brand 'lemforder', which in the fact is oem product. It's far cheap than the one marked 'BMW' but also made by 'lemforder'.

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--2004 E53 X5 4.8is - ECE version; right hand drive; Located in Hong Kong; ext. black sapphire metallic; int. leather black; adaptive dynamic bi-xenon headlights; 16:9 onboard monitor w/o navigation; 20" genuine BMW Y-spoke 214 wheels with Bridgestone Dueler H/P Sport tires; Int. rear view mirror w/ compass.