RE: ESC getting hot
if the motor is not hot then its not really geared wrong. An esc can get hot with different motors. Ecpecially going down in size. The esc has thermal protection against heat so if it were to overheat it will cut off till it cools down but its not good to keep running it hot time after time. It is capable to handle down to a 17t standard motor but the 19t that you now have is a modified motor. The esc cant handle a modified motor because of the advanced timing. You can use the xl-10 esc that can handle down to a 10t motor and even modifieds.