You can find all the replacement parts you need at Escapa.
Like theFSA Semi-Integrated 57E 1-1/8 1.5 15mm Aluminum Headset
Features:
Headset with sealed bearings
Use: Road/Urban/MTB
Material: Aluminum
Headset tube diameter: 1 1/8" 1.5 (28.6 mm)
Weight: 123 g