Randgust: Those Minitrix Fs were my main locomotives until the Atlas/Kato RS-3 came out, and even then they stayed in service. Three of them, jumpered together, were almost unstallable. That was important, because until we bought our current place in the mid 90s, my "railroads" were narrow shelves, held up by shelf brackets, around the walls of my bedroom. Not modular, or any benchwork, just whatever shelf width would fit a certain place.
Since all the layouts were good for was back and forth running, and some switching, reliability was more important than rivet counting... And those Fs were very easy to maintain, a drop of oil on the motor bearings every couple years, and take the trucks apart regularly to remove the cat hair. Didn't even have to take the trucks off to clean them.
Even today, especially with the addition of a flywheel, they'd make good train set locomotives.