Use a screwdriver to remove the dust bag from the side of the sander.
Remove the motor housing plate with the screwdriver.
Remove the screws holding the handle together to access the cord assembly.
Heat up the soldering iron and touch the tip of it to the power cord solder connections until they melt. Pull the wire leads free with needle-nose pliers.
Pull the old power cord out from the sander through the rubber cord support. Slip the end of the new power cord through the rubber cord support.
Hold the solder just above the wire connection pads and melt a small amount of solder onto each pad. Place the wire ends onto the pads with the wet solder and allow it to dry.
Re-assemble the sander's handle with the screwdriver.
Replace the motor housing plate and the dust bag with the screwdriver. Plug in the sander and power it up to test it.