Directions: How to Change Your Norelco Razor Heads: 1) Turn the razor off, remove the plug from the outlet and cord from the razor. 2) Press the razor head release button. Open the razor head assembly and remove assembly from razor body. 3) Turn the wheel counter clockwise and remove the retaining frame (Fig. 1). 4) Remove used cutters and combs (Fig 2) and insert new ones. Place the new ones in the razor assembly in such a way that the sides with the little holes point to the middle of the shaving unit (Fig 3). Make sure that the 2 pointy edges of the razor heads fit exactly into the recesses. 5) Replace frame on the razor unit by pressing down the wheel of the retaining frame and turning it clockwise (Fig 4). 6) Replace the razor head assembly back on razor. Place the protective razor head cap on razor to protect heads. Important: If you accidentally interchange the cutters and combs, it could take several weeks before optimal shaving performance is restored. Replace damaged or worn razor heads with Norelco HQ6 Quadra 7 razor heads only.