Another Moi export curio I've gotten stuck with...

I modeled three toruses that each have a ring set into the top, which I want to emit light in my render. Because "light rings" are embedded, I exported them separately - one right after the other, without touching anything in the MoI interface. (That way, I could import the light rings into Keyshot and apply the emissive material before the toruses got in the way.) Then I imported the toruses and applied a wood material. As you can see from the screenshot, the light rings are no longer on top of the toruses. The top one has widened and is on the outside, the middle one is, I assume, burried inside the ring, and the one on the bottom is squarely underneath.

Because of the odd placement (and, I assume, my lack of experience) I have no idea what's happened. Is it a scaling problem? A camera perspective problem? I exported both as .obj, without changing any settings or moving any cameras, and immediately imported to Keyshot. Any idea how to fix it?

Thanks a million for your help, in advance :)