@Jennifer76 To remove the door panel, first remove all the interior trim pieces: arm rest, door handle, window crank, and the quarter window knob. To remove the knob cover there is a small hole on the back side of the knob, I use the small side of a small hex wrench and insert it into hole then push from the back to pop off the cover. The knob is attached with a screw.
Once the interior trim pieces are removed, using a flat interior trim remover or a Phillips screwdriver with tape to protect your paint, start at the bottom and get the flat part of your tool wedged between the panel and the door and slide it left or right till you come in contact with one of the plastic attachment grommets. Carefully pry up till the grommet pops out. Slowly work your way around the door until all the grommets are out and the panel is held on only by the top chrome trim piece with the window felt.
To remove the panel, gently push from the bottom of the panel to pry the window felt chrome trim from the top of the door. I use the palm of my hand to give it a few pops on one end, then work my way across the bottom of the door panel until it comes loose.
With the door panel removed, if present, remove the plastic vapor barrier to access the internals of the door.
Based on what you've described, I think spraying some lubricant or oil into the door lock mechanism should do the trick.
While the door is exposed, now would be a good time to inspect and lubricate the window regulator and check your window tracks.
Hope that helps and hope to see you at the 02020 event on February 3rd
https://www.bmw2002faq.com/events/event/481-22st-annual-020202-show-swap/