RJV,

Sorry if I mislead you, 21 GRAMS really isn't a lot after a repair--I was thinking OUNCES for some reason. By all means, the plane should be balanced weight-wise--as discribed by gus. However, if you find it doesn't track well, there is a thing called "dynamic balancing" that will really help the plan to fly better. My Great Plans kit came with a matrix of how to dynamically balance an airplane for optimum flight performance. You can see a copy of it at http://www.stillwaterhobby.com/air/flighttrim.html. It may not be there much longer as the website has come under new managment, and will be completely redone.