I sat a square on the table, the blade is square to the table both up the side of the blade, and up the back of the blade. I made a little indicator with a couple of magnets sandwiched around a straight stiff piece of plastic. I can just about see when the blade is not parallel to the table for the blade removal. Now to pinch a couple of 45 degree plastic squares from the kids, and create a sliding parallel to check how parallel the blade removal slot is to the miter fence slots, and how parallel they all are to the improvised blade indicator. (I also used this to allow me to mark the effects of the wheel adjustment on the blade position on the back of the frame.