Windshield wiper arm with new sleeve (2):

Return windshield wiper system to rest position. Push wiper arm (1) with sleeve (2) onto shaft and tighten until hand-tight.

Fig 1: Pushing Wiper Arm With Sleeve Onto Shaft

Courtesy of BMW OF NORTH AMERICA, INC.

Set position of relevant wiper arm to rest position and then tighten down wiper arm.

Adjustment dimensions:

Observe tightening torque. Refer to  GENERAL ELECTRICAL SYSTEM - TIGHTENING TORQUE  . 

Fig 2: Identifying Wiper Arm Dimensions

Courtesy of BMW OF NORTH AMERICA, INC.