Exactly what Wayne just said. My Key USRA mountain has two screws in the back of the cab and one through the steam chest that need to have the pilot removed for access.
The boiler/cab assembly comes off very easily once all three screws are removed.
-Kevin
Living the dream.
I'm not at all familiar with that model, but it's very likely that there's another screw, hidden by the lead truck - you'll likely need to remove the lead truck to gain access.
Also, there are probably at least two scews at the lower back-end of the loco's cab.
Wayne
Recently got a gs5 from key imports. I'm trying to open it so I can install dcc. The tender was simple but I'm having some trouble opening the engine. I am able to pull part of the frame away from the top shell but it seems to be holding on right at the front of the engine.
here's a video of me trying to open the engine:
https://youtube.com/shorts/uY0hERho9DQ?feature=share\
As a said there seems to be something holding it in but I can't figure out what it is. I checked down the smoke stack and there isn't a screw its just part of the leading truck attachment.