I have a bit of play in the headset on Nighthawk. After enough miles Argon 18's revolutionary "3D head tube" must have gone a bit loose and needs tightening up.
The challenge is, my headset bolt has corroded with sweat etc. and the 5mm hex key that would normally work to disassemble the headset and inspect it just slides in the slot.
Any tried and tested ways to remove it? (I guess I'll need to swap it out for a new one anyway)