[jspatz1]

If you don't have the quality issues already mentioned such as misalignment or improper assembly, then your problems could be the result of too high of a gear ratio. A CIM motor just doesn't have enough torque to cause that kind of damage if applied with a typical gear ratio (6 to 15 depending on wheel size). If you are experiencing sheared keys and broken chains, then your drive could be seeing too much torque. Are you doing something unusual in the way of transmission? What is your gear ratio, wheel size, and robot weight? All three must be appropriate to work together. A picture or more info would probably answer this. If you suspect your drive ratio is too high, then lowering it will have the benefit of saving your chains and keys, and making you faster as well.