Bit of advice when it comes to servos.
Many servos will not work perfectly direct from the box. Especially the ones with metal gears. They need some run-in before they will perform their best. I've seen people complaining about their brand new servos in this thread. Airplane modelers always (or they should at least..) run their brand new gear with a servotester for an hour or so, so they know they can rely on the equipment.