There is another option for those who don't have the James Lee Wong and Keye Luke series. I have all six listed on one of my website's pages with links to each title.
Because the original copyright holders did not renew the copyright on the Mr. Wong films, they are now in public domain. This means that the Wong films are copyright free.
The Internet Archive website has many public domain films available for free viewing to the general public, including the Mr. Wong series. The web address is: www.archive.org.
An interesting note: Internet Archive lists six (6) Charlie Chan films as public domain, including "Charlie Chan's Secret" and "Dark Alibi."