Other than that mine ran terrible (because of the broken axle) I haven't actually had any issues with the loco getting hot or causing a short. Even with the broken axle, it pulled all 18 Morning Daylight cars.
I have new wheels on the way, so will be interesting to see if I came across any other issues once the new wheels are in place. It's definitely not Kato's best locomotive though. At least the learned from it, since the FEF-3 is supposed to be really good