The alternative to the above is to find a working locomotive with a "glass.bmp". Open, and then revert after copying the .bmp file of course.
Copy that file and rename it to glas.bmp and then put that in the above-mentioned folder.
Over the years, I've added to what I call a scrap box folder where I have all kinds of texture files and texture.txt files that can be used to replace missing ones. I called the folder because it reminded me of the old days when working on a model railroad and I needed a bit of something here or there for kit bashing or to fix something else.