GMC 2004 Envoy Owner's Manual page 362

3. Remove the insert from the blade assembly. The
insert has two notches at one end that are locked by
the bottom claws of the blade assembly. At the
notched end, pull the insert from the blade assembly.
4. To install the new wiper insert, slide the insert (D),
notched end last, into the end with two blade
claws (A). Slide the insert all the way through the
blade claws at the opposite end (B). The plastic
caps (C) will be forced off as the insert is fully
inserted.
5-54
5. Be sure that the notches are locked by the bottom
claws. Make sure that all other claws are properly
locked on both sides of the insert slots.
A. Claw in Notch
B. Correct Installation
C. Incorrect
Installation