Assuming you do get it apart down to the circuit board; DO NOT use a soldering gun to unsolder the dead bulbs. A soldering gun is not intended to be used on the delicate foil paths of a printed circuit board. It gets way too hot; it'll melt the copper foil along with the solder. The tip is too big for small work. And it also has a magnetic field near the tip which can induce voltage into sensitive components. Save the soldering gun for fixing the rain gutters. Use a small low wattage pencil with a fine tip designed for this type of repair work. Get a solder sucker or solder removing braid to help remove the old solder.

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Resistance is Futile.