Window wiper

If there is a plug over the pivot point of the wiper arm, remove it to expose the nut/bolt beneath it. (Tiny screwdriver/ knife blade).

Get the other wiper in the "park" position.

Now get a hold of the arm and put it into the park position too! (Sort of synchronizing/zeroing them together).

Hold on to him and tighten the nut you exposed a little more than it is now.

On many newer vehicles there are no splines that hold the arms, what holds them in place is a "taper", kind of a squeeze the female taper of the arm onto the male taper of the stud sticking up out of the cowl. Simply tightening the nut/bolt will anchor it to the stud better.

Crank them up to test the results.

Return here with good news!

The Medic

Mis-read you!

A small two jaw puller, or a

A plumber faucet handle puller may work too.

To remove the piece.

The Medic

The drive stud should have fine serrations on the taper that goes into the wiper arm. The nut on top pushes the arm down tight so those grip the inner taper of the arm. But if it has been run that way a while the serrations will chew on the taper and wear it enough that the wiper does not move. Then you tighten the nut on top and still get nothing, so you tighten it more and swear at it a few times when that does not work.

Now you discover the problem you currently have. Tightening the nut compresses the cheap metal of the arm above the serrations and it locks onto the threaded wiper pivot the nut goes on. Those threads do not go all the way down, there is a dead area just large enough that the metal can deform into it and lock the arm in place. The nut cannot tighten farther and the taper is wallowed out and the wiper arm just sets there.

Most of the time you can use a small puller to remove the arm. Then use a stiff wire brush to clean out the splines. (Most cars these days use the M8 style shaft in the image)