Southern Pacific's Jefferson Branch

[Charlie B]

You should check those proto gears closely. they crack on the axle shaft and allow the wheels to slip in the axle. I have had to repace every one of my units as well as all the ones my son has. It isn'ta badjob and the ones from the athearn sd40s are the same.  

You are making great headway and thanks again for the light tip. I got 3 boxes and like them so well I ordered some more for me and some for my sons layout (one I started in 1982.) I sold him the layout and included the house with it 

Great thread. 
Thanks for posting
Charlie