This same issue happened on my 2004 330 Larson Cabrio recently and thought I would update the post to perhaps help someone else. The cabin door would only open half way and then was stuck. Using the advise of this thread and a Rigid "In-Wall"camera I could NOT clearly see the obstruction by inserting the camera "botton hooked" and sliding the door open and closed. So after much thought and some time passed (using the half open door as a diet plan) I decided to cut the hole, there was no way I was going to disassemble the port side back to behind the cockpit fridge and try to get that back on and caulked.
At this point I was shopping for a tray like piece to fill the hole once cut. I looked for a rectangular tray with a lip to fill the hole, and eventually settled on a magnetic parts tray
https://www.amazon.com/gp/product/B01FL2C2CK/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1 that would be useful to hold keys, loose change, sunglasses, etc. So after cutting the hole, and had a clear view, it confirmed the camera was right, no obstruction to be found in that area. It turns out, the obstruction was under the first starboard track guide. So by measuring the distance to the middle of the track rail with a tape measure and then transposing that on the top (measure twice here, but the goal is to find the center of the track rail, give yourself enough room to slide the door a bit to get to both of the guide screws with one hole). I drilled ONE 3/16" hole, and used that hole to remove the first guide screw, then slide the door to get the second guide screw out. You need a skinny, and slightly longer Phillips screw driver for this step. Once the guide was loose, I was able to slide the door past the obstruction, and sure enough a track screw was laying in the center of the track. I remove the screw and started to position the guide to put screws back in the guide, this was a bit "surgery like" but was not too bad; using the same single drilled hole, I positioned the guide (blue lock tight, for crying out loud) the screws and screwed them back into the guide. I did not put the loose track screw back in the same hole, the track was still plenty tight without it. I did not need to cut the big hole in front of the map holder, it was not what fixed the problem for me; but I do have a nice magnet tray there now. (which btw there is enough depth for the magnets to fit). After caulking in the tray, and placing a weight in it, the job was done. This is a minimum of a 4 hands, 4 eye job, lucky for me I had 2 slip neighbors friends to help. Moral: Larson needs to use blue lock tight on these screws since they are buried with little access. I simply filled the hole I drilled with a stainless steel screw to fill that hole.
Just wanted to share that if the obstruction is in an area such as mine (more on the starboard side of the door) it can be fixed with 1 small drill hole, and some patience. Since the door now opens up all the way again, its time to fire up the grill, "the half open door diet is over"!
OTM