I have the photo set that Tom Klinger sells that shows 8 different views of this incident all taken by Ben Zwibecker (including the photos shown on the forum). The turntable has four rails and one of the photos shows the table directly lined to the roundhouse stall next to the track that the 485 was sitting on. Looking at the photos, I agree that the engine walked the wooden edge of the table and only fell sideways into the pit when the entire weight of the engine and part of the tender became too much. The entire set of photos really tells the whole picture of the extensive damage that the engine suffered.
Daniel