2 speed motor not working correctly

New to the hot tub world, but mechanically inclined. Filled hot tub that I received from a friend...was working just fine. Pump #1 (2 speed) only will work on high... makes humming noise on low until some type of thermal overload trips. Turn power completely off to hot tub for about 10 minutes...turn power back on...tub tries to turn motor on and it just hums...I can press the button and high speed kicks on no problem. Push the button again to go to low speed and it hums...if I dont press the button again to go to high speed, which turns on no problem, it will trip the over load...this is a pain cause the motor will only stay on for 20 minutes (normal operation time)

PLEASE HELP
:confused::(