span style='font-size:18px'>Step 6 -/span>Slowly begin to press the upper headset cup in, stopping after it first enters the head tube to ensure that it is perfectly square and straight. It isn't uncommon for a headset cup to rotate slightly before it is deep enough in the head tube to prevent it from shifting - take your time and inspect the alignment with each full turn of the headset press' handle. If it shifts at all, even the slightest amount, you'll have to remove the cup and start over.