Nine times out of ten, the call is "my skylight is leaking." Nine times out of ten, the leak isn't from the skylight itself — it's the flashing around it, the underlayment under it, or the shingles tied into it. Skylights take the blame for failures that happen six inches away from them.

So the right way to replace a skylight isn't to swap the unit and feather the shingles back. It's to tear out the surround entirely: shingles for two courses around the opening, the old underlayment, the old flashing kit, the old curb sealant. Drop the new unit in. Lay self-adhered ice & water shield right up to the flange. Install the manufacturer's flashing kit (matched to that exact unit). Reshingle. Done. The skylight isn't a special place anymore — it's just another sealed penetration like a chimney or a vent stack.

If we're already doing all that, you might as well replace the unit while we're up there. Velux units made before 2010 are at end-of-life. Newer ones run circles around them on glass coatings, energy efficiency, and venting/solar options.