Range Slider requirement/default value

Greetings,
I am using CF7 with multiple range sliders for use in a survey. It is critical that each slider been adjusted and not just left at the default value. Adding each slider with a required * doesn’t seem to work because the slider will just take the default value if it’s not adjusted. How could I go about making sure that each slider is adjusted before the user is able to submit results?

Appreciate any thoughts. Thanks.

Nate