Reply by syenefarmer

Maybe try spraying some PB Blaster Penatrating Catalylist around the arbor nut. Do this a couple of times during the day, let it sit overnight to work its way into the nut and then try loosening the nut the next day. Wedge a piece of scrap against the blade then clamp the scrap piece to the table top so it will not move. After you have the wrench positioned on the arbor nut give it a good wack with a dead blow hammer or rubber mallet. Good luck.