Product review (5 stars): Easy Fix for Anyone
If your washer is shaking during a regular washing load, you need to get this.  It is a bit tight to get them into place, but not too difficult.  If you have short arms you might have a problem getting the old one out.  You do need some strength to pull the rod up and overcome the spring pressure to set it in place.

The washing machine is now running like a new unit.

Youtube has videos of how to replace the parts, take a look and see how to do it before attempting.