Originally Posted by
PromptCritical
I put the cups in firmly with the Park tool, and they headset has loosened multiple times. Indication of the head tube needing to be faced (It's an eBay Colnago frame, so I don't know the history) or bored out so the cups are loose?
If the pressed fittings keep coming loose, you can use a bearing retaining compound, like Loctite #609, to secure them in the head tube.