Nice work Steve. I have a similar "Type B" that came with a M-10000 set (I have the train too). I've tested mine and it works fine but I do need to change the cord. Good to know what I'd be up against if /when I open it.
The set also had Lionel's # 95 variable rheostat.....now this does have asbestos in it so it's wrapped in plastic for now. And yes- I know how to handle the stuff.....
Bob