Walther PPK/S Problem

General Firearms Handguns - Semi Auto
1

I have two Walthers, a Manurhin PPK and an Interarms PPK/S. The Manurhin works perfectly. The double action on the Interarms is faulty.

Video:

http://s206.beta.photobucket.com/user/Andrewsky89/media/newestphotos011_zps3f76c0ef.mp4.html?sort=3&o=0
Photo:

What is the problem, and what can I do to fix it? I am not aware of any decent gunsmiths in my area. I went to one today who was completely clueless. He told me to change the grips.

http://www.gunpartscorp.com/Manufacturers/Walther-33560/PPK-42534.htm?page=3