With the front brake jammed on, grasp the bottom of the steerer and the fork crown; rock the bike back and forth: you'll be able to feel any movement of the fork.
If there is movement and the headset is tight, I'd disassemble and check for damage to the races or bearings.
With the front brake jammed on, grasp the bottom of the steerer and the fork crown; rock the bike back and forth: you'll be able to feel any movement of the fork.
If there is movement and the headset is tight, I'd disassemble and check for damage to the races or bearings.