Chosen Solution
How can I remove the hold down nails {to be replace with insulated screws[from the corrugated metal roof without damaging the metal roof? is there a nail puller that pulles straight up and not pried up.
You may need to fashion a block of wood that conforms to the metal roof to spread the pressure of the hammer claw/crow bar base as you pry the nail. I took two blocks of wood and two pieces of 1/4 steel placed across as short a distance as I could between the blocks. Then resting the hammer on the metal bar pulling the nails. In my case I had raised over-lapping seams. If you have corrugated roofing that will be harder depending on where they nail it down.
