I do not have the repair instructions, but I am wondering if there is a difference between the model released in 1940 and the model released in 1945? I have repair instructions for most post war models such as the 252 Crossing Gate, but the instructions for the 152 is not included as post war. I am thinking that perhaps what you are looking for is located in a pre war collection of repair instructions (which I do not have).
If I am correct, the source you need is "Greenberg's Guide to Lionel Prewar Parts & Instruction Sheets"