Thanks fellas for the good advice.
After just a 30-minute wait on hold (I expected much longer), I spoke with Louis at Colt Customer Service. He said that firstname.lastname@example.org
was deactivated a couple of weeks ago due to the volume of mail they couldn't efficiently keep up with.
Louis at COLT suggested basically the same thing / a vigorous cleaning and polishing and then test firing it.
Will try the suggestions I've received tonight and will report back to the board with hopes, if successful, the solution may be helpful to future forum members and visitors.
If problem persists, he said to call them back and they'll issue a postage-paid Return Label. Said to return upper and lower so they can test fire before returning.
Just found your forum last night while Googling my AR situation. I couldn't be more impressed with the professional attitudes and expertise of the folks on TheFiringLine.com
Thanks - Steve