After removing the head and carefully marking everything, No1 TDC, crank on it's timing mark and camshafts locked off. Upper chain secured and witness arrows on variable timing my roller count between sprocket markings is only 12 instead of the 16. Is this a case of lifting off the upper chain, winding on the sprocket to it's stops and replacing. Then checking for the 16 rollers? Any help or comments would be appreciated.