Inaccurate animations when exported to Railworks.

I suspect that there’s a problem with rounding of floating point values. I’d animated a loco cab control which was a wheel (the proper word for it usually gets deleted automatically from posts … can you guess?), so it simply had to be turned through 360 degrees. The wheel has a shaft that goes into a valve (that is a separate, static part of the model). It animated perfectly in 3DC but when I ran the animation in TS2013, the end of the shaft nearest the valve wobbled a lot, following what looked like a random path around the true centre.
There is a sort of a solution. I looked at the x-y-z axes of the group centre (the group containing the wheel object) and saw that they were aligned at 0º and 90º with the wheel shaft. I shifted the object so that it was aligned instead by 45º in each axis. then reanimated it. The exported animation was much smoother, staying fully aligned with the valve except at in the very last step of the animation timeline, where there was a slight jump.
I think there must be a problem when computing angles, or when using angles to compute positions, because the problem occurs when one of the axis is aligned along the same axis as the shaft.