Usually a problem like this is due to the slow down or leveling magnets having the wrong polarity. At the 1st floor if all the magnets are north, the next floor should be south. The next one north etc; etc; White is south, black or a groove is north. If the polarity is wrong on a magnet the floor count goes off in the weeds, and the car doesn't slow down. also check the running clearance on the sensors. It should be near 3/8",
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