Sticking Piano Keys Caused by Sluggish or Tight Action Parts

One of the most common causes of sticking piano keys is having tight action parts.  The following video gives more detail about identifying if your piano has tight action parts.  This video also includes a clip showing a piano that has a major problem with tight action parts.  Here are a couple of other videos related to this that you may find useful:

Diagnosing the Sticking Piano Key
Fixing a Sticking Jack
Piano Flange Repinning