Now I'm not sure what the exact parts are called, but this is an Alpe d'Huez 2005 which has some play down the steering tube. I will provide a picture of what I mean:
The red box represents the steering component of the frame. The yellow line represents the centerline of the steerer. The play of the yellow line where the headset is located is roughly 1 mm. I'm afraid of fatigue cracking in the frame, since this is an aluminum frame. So far I have not found any cracks, but this must be prevented at all costs.
When I open up the screwcap on the top of the steering tube, what I see is a star-flanged nut, and I can't reach the bearings. How do I open this up? Or ultimately, how do I fix the play?