Gilbert American Flyer made a variety of train motors based on the various train models they were manufacturing. In general, the motors were designed to match the type of locomotives they were modeled after and had a variety of features. It appears that there were approximately 6 different types of American Flyer Train motors as well as a variety used in accessories and other components.
The first American Flyer Set produced also came with track, an uncoupler, and a transformer. The “T” in the set number indicated that a transformer was included. The set was cataloged in 1948 and 1949 and several un-cataloged versions also exist. 1948 versions should have the brass coupler weights and the 1949 versions should have black coupler weights.
So you have an old Gilbert American Flyer Train Engine that is broken or needs service. This page will provide you an index and links to the appropriate original service manual. The left column provides the original American Flyer Locomotive part number and the right column is the link to the manual itself.