Chevrolet Impala 2007 Owner's Manual page 350

To remove and replace the wiper blade element
do the following:
1. The wiper blade element has two notches at
one end which are engaged by the bottom
claw set of the wiper blade. At the notched
end of the wiper blade, pull the wiper
blade element from the wiper blade assembly.
2. To replace the element, start at the heel end
of the wiper blade, which is the end nearest to
the base of the wiper arm, and slide the
wiper blade element, notched end last, into
the wiper blade claw sets.
3. To engage the last claw into the notched end
of the wiper blade element, squeeze the wiper
blade element at the notched area, and
push the wiper blade element so the claw fits
into the notch.
4. Be sure the two wiper blade element notches
are engaged by the last claw set, and that all
the other claws are properly engaged in the
slots of the wiper blade element on both sides.
350
A. Correct Installation
B. Incorrect Installation
For the proper type and size windshield wiper
blades, see Normal Maintenance Replacement
Parts on page 419.