It is really easy. There are 5 screws. Yes parts can fall out but it is not a big thing as they only go back one way and is not complicated. Don't open if under warranty.
WP Steve
I have no idea how I would open one. Are they glued or heat melted together. And if you open it do parts start falling out?
Paul
Modeling HO with a transition era UP bent
Over the years I have had the Tortoise switch machines fail on my layout and had to replace them. Not many but some.. Had one go bad last night and not having a replacement I took a look at one in the save for parts box.. They use the case for bearings and it is soft plastic. The shafts on the gears are really short so it take little wear and the gear slips down in the bearing hole, The main problem appears to be the main throw arm. It really is an easy fix.. Just rebuild the bearings with new plastic. On one it was the upper half of the bearing and I just made a half slot with a file in a 125x125 piece of styrene, cut a slot in the case to hold it and all was fine.. Another one the slot had worn down into the main case so I just put a new piece if flat stock with a half hole filed with a round file.. Really just a few minutes to repair. Can't say how long it will last but if it happens again I will just use stronger plastic !
Also I recommend using a stiffer wire than they provide as the one supplied looses it strength fairly quickly.. Still like the Tortoise, more now that I have found they can be repaired, Had the wiper break on one, have not figured out a fix for that yet !