Dewalt 20V Circular Saw Blade Keeps Slipping

Hello,

I have an old Dewalt 20V 6.5in circular saw whose blade keeps slipping when I try to use it. It looks like the washer/screw assembly that holds the blade is missing some components.

What is the best way to find and order the missing part numbers.

Thanks 

Google the “(model number) parts” 

Try E-replacement Parts part #N621119 is the outer washer ring clamp but I think you need a new inner washer part #650109-00 or you can stack 2 blades and offset the teeth.