Been away from the game for a couple of years and the new interface for upgrading ship components is a little confusing. In the past, when I upgraded a component, I got a credit for the old component. Now it seems that you have no choice but to store the old component. Have trouble figuring out how to sell, but occasionally stumble onto how to do, but the sell value is zero. What's up with this? Is there a limit on how many ship components can be stored?