usually servos conk it (generally the throttle servo ) due to the user setting it up incorrectly.
any servo will eventually bust if loaded up enough. i can vouch for it, unfortunatly i've ruined a very good ko propo metal gear servo by setting it up incorectly on the throttle. luckily i bought it second hand and i didn't cost me a arm and a leg.
the 3003 futubas work well for a throttle servo.