My DeWalt D28770 band saw does not turn on. It several years old but has been used minimally. The switch works and sends power to the "controller", which I assume is the variable speed controller, but nothing happens. How do you check the controller. Does the controller have any serviceable parts or do I have to purchase a complete unit. I'm looking for options, as the controller is $137. Can I bypass the controller and make the saw run at full speed?