Although not a Hawkeye, I am guessing it is possibly the same principles as Dave shows in this walk through. Unfortunately, many of us who have pulled apart the headlight units have found (however well we have sealed the units after) that water can still get in and mist up the lights, so bare in mind its not a quick and easy job.
http://www.southeastscoobies.co.uk/v...ighlight=tango