I recently purchased this item from a seller on ebay. The quoted condition was C-6. It is painted red and according to what I have read it was an early model manufactured in the late '40s. It was missing the lens and light bulb, but the lens base was included. The item is in quite good condition with all metal framework including the ladder structurally perfect I ordered from other vendors a new repro lens, light bulb and, just in case, a new repro lens base. First, I installed the light bulb and placed the lens on top so it would rotate freely. Then, I hooked it up to a small test transformer and the bulb lit. Thus, the accessory worked electrically. But, as I expected, the lens would not rotate even up to 18v. After about 5 min, the lens got hot. Had to turn it off to prevent a lens meltdown. A closer look at the base revealed it was not seated completely in the tower frame. I thought I had found the culprit. But the base would not seat; it would raise up on the opposite side when I exerted careful hammering. I removed the base, examined it and the platform it seats in. Saw no observable reason for the seating problem, so installed the new base, which seated completed and reassembled the parts. Then, tested it again with same results. Lastly, I dug out my Greenberg's Lionel Repair and Operating Manual to see what might be the problem. Recommended were two solutions: check that the lens' vanes are equally opened (no info on how open they are supposed to be); and try bending that pivot needle inside the top of the lens. As far as the second reference, I don't want to go there. I can envision breaking that needle, which will render the lens useless. Plus, the lens appears to my eyes to be level; and it will rotate quite a few times with a manual spin. Not specified in the manual is the appropriate voltage to operate the lens without causing a meltdown.
Sorry for the long winded description of my problem, but I wanted to describe as completely as I can what I have done to save posters time when responding with suggestions. I am aware that repro parts can sometimes be a problem, as the lens or the dimple bulb could be out of specs. Any advice/help provided will be greatly appreciated.