Can someone tell me how to correctly remove the plastic door-post trim so that I may access, clean, and lubricate the front driver side seat belt mechanism?

 

it seem to be a hard job, I think you can't do it alone try to ask for assistance of a pro.

 

I too agree with him that you cant do it alone.its better that you take some help from some one.

 

The trim has an upper and lower half that wrap around the post. The wrap edges hold the trim onto the post frame.

If you carefully pry the edge of the trim off you will see how its held on.

Unfortunately there seat belt retraction mechanism is sealed in a case. You might find that after removing the trim the belt retracts OK in to the mechanism and is hanging up outside the unit.