Steerer has play fore aft, none side side. You can see the top bearing slide fore aft in the cup. Tightening down doesn't stop it. I replaced headset, including cups, with new headset with cups perfectly tight to bearing in all directions. After pressing in top cup exactly the same issue as with old headset - fore aft looseness but tight side side, can see bearing slide fore aft.

I'm therefore pretty sure my headtube is ovalized. It's not a lot, but it transfers into unacceptable movement at the wheel over the distance of the lever. And I assume that it can get worse as the head tube over and over again has to stop at the momentum of the free swinging steerer every time I break hard.

Is there a DIY fix? It's an almost brand new frame, Salsa Fargo steel. I live in Seattle and there are a couple of super experienced steel frame builders in town here. I'm sure they could cut out the head tube and put in a new one, but I'd also bet that might be $500, maybe more with the need than to repaint the frame.

Thanks for advice