I haven't begun yet, but the PCB for the roof vent failed and a replacement is $189. I'm thinking I can make some mods that won't require the PCB. a double pole, double throw momentary reversing toggle switch for the vent lid motor and a PWM (pulse width modulation) controller for the fan. The two switches are less than $30. Pulling in new leads is the one thing I may have and issue with. If the current lead from the control panel to the fan was stapled when they installed it that will be a problem. Am I overlooking something that makes this undoable? The fan has a brush motor so the PWM controler will work.