A servo with 1/2 the torque will be very undesirable... should be same amount if not more...take a look at amazon seen and purchased many servos from them..needed a 1/16 scale high torque servo went to lhs to see a 40$ servo found 1 on amazon for less than 6..its been running my boat for 3 years...
do you have any other servos to check the rx? .if not do you have a servo tester? my new charger has a rx tester and a servo tester on it...you can turn car on but disconnect motor so you dont get hurt put your ear or if you have a old school stethoscope to listen to A motor.use it against servo...