I definitely agree with onimity about having it checked over by your LBS. We had a customer this week bring in a bike that appeared to need a new headset. He purchased his Ellsworth off of Craigslist at a great bargain. It appears the headtube is ovalized. The usual culprit to this is a frontal crash - obviously not listed by the seller.

Just be carefult purchasing used. Used bikes carry no warranty - manufacturers or bike shop service.