Armature sizes

El Classico posted:

Did Marx make a smaller armature than its standard size? Can a small Lionel armature replace a Marx one and the Marx engine still run smoothly? I ask as I have made some lovely repairs to my Marx 495, and for some reason the armature is knocking due to its diameter.

Marx may have made different sized armatures, but you cannot substitute a Lionel one. Maybe yours is knocking because someone did a substitution at some point. More likely is that the armature bushings are worn out or not in proper position. On the gear end there is either a flat spot or a notch in the frame to accept the bushing and lock it from rotating. On the brush end, the fiber plate does a poor job of bushing the armature and often wears out of round. http://www.trainpartsformarx.com/ sometimes has replacement brush holder plates.

Thanks for the information. Forgot I posted here, as I fixed it not long after. I had to countersink the minuscule bolt I used to attach a Lionel pickup roller, and fabricate a new brushplate using what might have been a 490 side frame and some sealed Lionel brush wells I had on hand.  She runs beautifully now, and actually has a tendancy to throw herself from the tracks if I go too fast, which was a pleasant surprise.