Hi Brian. I use a Wixey digital angle gauge to square my blade. First I unplug it then I zero it out the Wixey on the SCMS table, loosen the stop screws, set the blade to 90 deg. and retighten the nuts while making sure the blade doesn’t move. Then it’s just to recheck with the Wixey to make sure the blade is in fact a 90deg. If you don’t have Wixey, then you can use a square.
It might help to lock your blade in the closed position when using a square. This can be a little clumsy as the blade guard has to be somehow held in an open position while testing for square or removed.
The blade guard usually has a little tab that’s used as a handle for opening it manually and you might be able to tie some string to that and fasten the other end to the saw body to keep the guard in an open position while you test with your square.
Mike, an American living in Norway