First, if it's newish....send it back to Viking as Mike Webb said. Otherwise, to replace a joint pin (on the assumption it's the issue) should be done by a competent repair guy. Removing the pin can damage the collar and finish if not done right. Plus, once you TRY to remove it, the pin is trash whether you get it out or not, and the warrantee is trash also. Once the pin is removed, then a tap is needed to clean the threads in the hole and install a new pin, properly, all while maintaining accurate centering of the pin. All this being based on the Assumption that its the pin.
Does the cue have a Stainless steel collar? If so, give it a twist to unscrew it, if it moves....there's your problem. Could also be a buzzing 'A' joint, loose buttcap, loose weight bolt, and have even seen a loose bumper cause a buzz
Dave