You should check the resistance of both sets of windings. If anything shorted out it should be obvious when compared to the standard readings. I think the K7000 yoke reads around 9 ohms and 2 ohms but I can't access my chart right now. I'll verify that when I get home.
Look for loose screws/pennies stuck in the yoke that might have gotten trapped in there by accident. I dumped a bucket of tokens once and had some pennies get stuck under the yoke. Didn't short out but made a goofy picture.
Only time I smoked a yoke I plugged it in incorrectly. (It still worked when I fixed it)