Mine's original and I've never had a real problem. The mast got snapped off in the carwash about 6 months ago and I replaced the mast with a $16.50 MTC instead of a $45 Hirschman. I don't know what I was thinking in the first place but it's def a $16.50 mast. I'd never do it again and learned my lesson, Hirschman all the way.

I do regularly clean and lube it though so maybe that's why it's lasted so long. Mine's an '83 and I do think they changed the motor assembly somewhere along the line.

On mine there's a wheel on the gear that counts "clicks" as it rotates to tell it when it's fully up and when it's fully down so the failure to retract completely may be a result of mast installation and if the gears turned too many times before it caught the new mast to retract it. Also, make sure the plastic sleeve and antenna are fully seated against the stop inside the case. That gave me a few problems when I installed my new mast.

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'83 240D