NormanHarley wrote:
Thank you, I didn't know that. This one is a flat head screw, not a Phillips. The head is flush with the surface as it sits in a head sized, machined cup in the aperture ring, not sure if oil would penetrate around the head, into the cup, down the threads and then on down to the threads in the mounting plate... and I don't want to get oil all over, I am making enough of a mess with the metal shavings. :-(
My technique works for any mushed screw head. Tap on it gently with a hammer or pin punch driven by a hammer, work the damaged metal back into original shape as much as possible. You can apply oil sparingly with a toothpick or small hobby brush. Capillary action will usually draw liquid lubricant (oil) down into the threads.
You can also use a Dremel with a thin cut-off disc to cut a new slot in a screw head or screw shaft.