End stops not included to hold MGN12 block to rail. Mine shipped with no problems but I can see how the end can slip off during shipping. In this case, you may receive a bag of ball bearings that need to be reassembled. Slow train rides are extremely bumpy and bumpy, not smooth. Seems smooth at higher speeds. I haven't tried cleaning it, but I didn't have to clean the other rails when I bought them. They come sealed and well lubricated.
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