Subaru Impreza 2016 Owner's Manual page 528

2. Pull the blade rubber assembly out of
the plastic support.
1) Metal spines
3. If the new blade rubber is not provided
with two metal spines, remove the metal
spines from the old blade rubber and
install them in the new blade rubber.
Maintenance and service/Replacement of wiper blades
4. Align the claws of the plastic support
with the grooves in the blade rubber
assembly, then slide the blade rubber
assembly into place.
Securely retain both ends of the rubber
with the stoppers on the plastic support
ends. If the rubber is not retained properly,
the wiper may scratch the rear window
glass.
5. Install the wiper blade assembly to the
wiper arm. Make sure that it locks in place.
6. Hold the wiper arm by hand and slowly
lower it in position.
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