i did. I don't have a file so i resorted to using sand paper. Due to uneven distribution of the sanding technique the back of the fire box is slanted a little bit.
My Trackmaster/Tomy/Plarail Photo Gallery Page (over 600+ photos and still under construction)
https://www.flickr.com/photos/183311600@N03/
https://www.flickr.com/photos/183311600@N03/