I've been reviewing this elliptical myself (interested in buying one) and for the most part it's gotten good reviews. One person said she had knocking but after reading the troubleshooting section of the manual it was obvious that there was a simple sensor adjustment that was required. After making the necessary adjustment it works great. Not sure if that helps you but try it. If not look at the troubleshooting section in the manual and maybe you'll see something there...... Best of luck. Julie
Julie
January 2009