Before you replace your webcam, make sure you have a good network connection, your computer isn't working overtime on another application and your webcam driver is current.
Older webcams than 2006 may not perform adequately. Audio or video may work but not both together. If your network connection is good and your computer is not be over-loaded, then perhaps you should get a new webcam.
Try disconnecting and restarting your video call to see if video or audio improves.