It must be balanced just now? Also is it not balanced outside the turbo, then marked up, dissmantled and then re assembled inside the cartridge. So whats stopping you marking it up, dissmantling the turbo, replacing the worn seals and bearings, then re assembling it. A turbo cant be balanced assembled! the material removed to balance it is usually removed from the back of the compressor wheel and turbine wheel. This cant be done when its inside the cartridge, therefore it is totaly posible to take it appart and re assemble it as long as it goes back together the way it came appart, and the shaft and wheels have no damage. an engine is balanced, but you can still take it appart as long as it goes back together the same way.