51 13... Adjusting windscreen frame seal to roof shell seal

Release outer screw (1) of windscreen frame seal (3).

2 = banjo nut

Fig 1: Releasing Outer Screw Of Windscreen Frame Seal

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Turn banjo nut top adjust windscreen frame seal (1) flush with roof shell seal (2).

Fig 2: Adjusting Windscreen Frame Seal With Roof Shell Seal

Courtesy of BMW OF NORTH AMERICA, INC.

Sectional view for improved clarity 

Banjo bolt (1) alters the relative position of vulcanized aluminum sheet (2) to windscreen frame edge (3).

Installation: 

After adjustment, secure banjo bolt (1) again against twisting with Loctite.

Fig 3: Securing Banjo Bolt

Courtesy of BMW OF NORTH AMERICA, INC.