Don't know how many planes you have, but I basically have gone with three basic servos, all JR (3421SA, 9411SA, and 8411SA) for all my planes. If I need to temporarily borrow from another plane, I can do it. The best way to go is to have a couple of each new in the package laying around when you need a replacement. Then again, the longer you're in the hobby, the more you tend to accumulate and will likely have extra servos and receivers, etc laying around.