repairing that antenna is a piece of cake,

remove the extended bit by unscrewing the nut and allowing the motor to extend it, once removed, - undo the carpet panels and remove the one nut holding the assembly in place and take it to the bench for repair.

I also make sure to oil the antenna mast after every wash, an oily rag is all that is required.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)