Excessive vibration on spin cycle.

Front loaders are prone to vibration problems. Don't want to go into the technical details of why, but it's important that they're placed on very solid surface (preferably concrete or tile), and checked that their feet have been adjusted so that the machine is level. Unfortunately, most people don't have a concrete pad for their washer. One simple option to consider is to provide dampening of the vibrations. This can be done very simply as this one fellow demonstrates. The main thing to keep in mind with this solution is that it is merely trying to dampen the vibrations. Don't be too forceful in your own solution (think lightly touching the top of a vibrating tuning fork with your finger to stop the tone).