Maybe your 300 SD is different. My 300D and 240D both have a black metal ring that unscrews. I can't picture how you are using needle nose pliers on the round smooth ring. Use you fingers! Try a stronger poker like the dull end of a small drill bit instead of a paper clip to push in the pawl and see if you can get the ring off.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked