First off sorry for the poor quality of the video...Here is how to break-down a Winchester Model 1885 for cleaning. This applies to both the Low Wall and High Wall. I made this video after finding information on disassembly to be hard to find and hearing these were difficult guns to take apart. I went ahead and took mine apart and found it to be quite easy and takes under 2mins so I thought I would make a how-to video.
First remove the stocks, two screws on the butt one on the fore. Then remove the two trigger group screws and pull the assemble out the back of the receiver while pulling the lever back to give the trigger clearance. Removing the tension off the mainspring first would probably make this easier. Once the mainspring screw is backed off, but not removed, back off the lever pivot pin set screw and pop out the pin with a brass punch. Next pull the lever/bolt assembly out the bottom of the receiver along with the extractor. Make sure to push the sear out of the way with your thumb while doing this. To get the lever separated from the bolt pop the upper pin out. Assembly is the reverse.
Note the rifle in the video is an original from the 1800's, I do not know whether this will apply to the newer reproductions.