It has been a long time since I've ridden that train, highly recommended BTW and be sure to tour the shops.
The state park web page (not the Railtown webpage) has a map with clues. Railtown 1897 SHP
You want the park brochure.
Then take a look at google maps satellite view. You can see the loading platform. As I recall, it heads south from there then reverses and takes the NE branch after it passes the water tower. I think if you compare people's photos and videos with the satellite map, you can confirm the route.