Join Date: Apr 2007
Location: Powell River British Columbia, Canada
Use a thin "magic bar", tap it up under the bottom of the board, and pry very gently. Work your way along the board until you have some clearance under it. Then push the board back in, and hope the nail heads stay out. Pull the nails out, and then do the same on the board above. If the nails won't stick out enough use a nail puller. This will leave some dents in the board, but as you are going to repaint any way, you can fill the dents before painting. The big trick is to be very patient. The top edges of the boards are very thin and easily cracked.
I just salvaged a whole bunch of siding this way, so I know it works.