Hi Dave welcome to the Village. I'm Marg from Australia. I have a DeWalt and if I have a problem with a blade slipping out I take out the screw and just give it a light sand and also run the sandpaper up and down on the opposite side. Plus when I need a new blade I rub the ends over with sandpaper and just to had a little overkill I dip the ends in alcohol too. Problem solved for at least 6 months or more.
Marg