Forgive me if you are doing this correctly, but you are tightening the top cap with the stem pinch bolts loose, right? Have you checked carefully to see that the head tube hasn't ovalized or cracked, allowing one or both of the cups to move? Are these cartridge bearings, and if so, do they appear to rotate smoothly? do the cups appear to be in good shape? The races too? Just trying to get as much info from you as possible so that we can properly assist.