Product review (5 stars): Z Line Range Hood Insert 695-28 Review
I purchased this item in May 2015 and installed it in July 2015.
From time to time it would not work when the buttons were pushed.
I found that unplugging it and plugging it back in would easily correct the problem.
Early this month (February 2017) I called Z line and explained my problem.
Their customer service was great.  They quickly sent me (at not charge) a new button control module and a new main circuit board and instructions for replacing these.  I tried replacing just the button control panel as per their suggestion.  This did not fix it.  However, replacing the main circuit board did fix it.  I am happy with the purchase.  Also note that their website now mentions a lifetime warranty on the motor.
I would recommend their products based on quality and customer service.