Definitely wheel gauge. Since it's brand new, it can't be cat hair. I just had the same problem with a LL BL-2, the wheels were in gauge, but it kept picking a particular switch.
When I looked more closely, there was a bunch of crap wound around the axle, which was preventing the necessary side-to-side slop that allows the wheels to wiggle through the flangeways. Cleaned it out, reset the gauge, no problem.
Lee