Do your windshield wipers leave unwiped spots for no apparent reason, even after you replaced the blades? Chances are the hinge is binding from corrosion. We'll show you how to replace the wiper arm and fix this problem.
Splines on the inside of the wiper arm fit over splines on the shaft.
Lift the plastic cover and remove the retaining nut. Then pull the arm off the splined shaft.
Lift the wiper arm a few inches off the glass and slide the locking clip out. Then lower the arm and pull it off the splined shaft.
All wiper arms have a hinge at the base that allows the arm to flex as it follows the curvature of the window. If the wiper skips over certain spots, even with a new blade, chances are the hinge is binding from corrosion. It's most common on rear window wipers since they're used less often.
You can oil the hinge, but that's just a temporary fix—the corrosion and binding usually return. To fix the problem permanently, replace the wiper arm (available at an auto parts store).
All wiper arms fit onto a splined shaft (Photo 1). Some are held in place with a nut. To replace that type, just lift the protective cap, remove the nut and pull off the arm (Photo 2).
The other type is held in place with a locking clip. Unlock it as shown in the bottom photo and install the new arm (Photo 3).