I recently was able to get an older jointer for free and am in the process of cleaning it up to use. I have been trying to find blades for it but I’m not sure exactly which ones I need to get. Finding several online that are the right size but they are all straight with no grooves (I’m struggling to remember the proper term for these attachment grooves) which I need for the attachment style. The jointer is a Rockwell Compatcool 4″. The blades measure 4 1/8″ x 5/8″x 3/32″. If anyone knows of anywhere I could find these parts or any replacement for the head that would eliminate this I appreciate the help. Pictures of tag and blade attached. 

Thank you