I thought you were very firm in sending all your mechanical work to the shop instead of doing it yourself?
Is this an expander
plug in a carbon steerer, and has a bonding agent been used on it to prevent it from working its way up the tube when the headset bolt is tightened?
Looks to me like it's rooted, especially the threaded bit where the bolt goes in. A bit of careful drilling might be called called for -- it's alloy, isn't it, so should be soft enough to drill out;