The air button on your tub may be bad and not sending enough air to the air switch located on the bath pump.
The way to check this is to remove the bath pump and see if you can turn the bath pump on by taking a large straw and blowing into the air switch on the bath pump to see if you can get the bath pump to turn on.
If the bath pump comes on then you know you have a bad air button.
If you cannot get the bath pump to turn on then remove the air switch and plug the two wires going to the air switch together and then plugging the pump into a power outlet you know has power.
If the bath pump comes on then you know you need a new air switch in the motor.
If the motor does not come on then you need a new bath pump.
RodUS Parts Center