Thanks for the advice, we did perform some of the suggested remedial action:

Is the gas port clean ? We did clean it with a pipe cleaner
Is the magazine tube clean ( outside) ? Clean with a scotch brite pad and oil and wipe oil off I don't understand what you are telling me to do here?
Is it just 1 brand or type of ammo or reloads ? Nope, had several mix and match factory loads
Is the gas piston on the right way ? Yup, checked the book
Has anything changed between when it worked and now ? We have taken it apart about 50 times, but that was after the problem started
Is the O -ring on and in the right spot ? Checked the book, looks correct to me
Are you over oiling it ? Nope, both of us spend a little time in the desert with an M-16, learned that lesson

He is in the process of repeating all the above just to ensure we didn't miss something before contacting the company. I hate to feel stupid and I know it is most likely something simple that we are doing wrong. Thanks again for the suggestions.