Berryman's 0996 might clean that right up. It is safe on plastics. Let it soak.
Resist the urge to scrape, possibly damaging steel/composite sealing surfaces.


Cheers

snapped_bolt

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'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....