Whether it be electronics, automobiles or medical equipment, the manufacturers should not be able to horde “oem” parts, render your stuff useless if you repair it with aftermarket parts, or hide schematics of their products.
Summary video by Marques Brownlee
Great channel covering and advocating right to repair, Lewis Rossman
Basic blender went bad (motor ran but spindle wasn't rotating). I wanted to disassemble to see if it could be repaired. Three of the four screws were Phillips head. I had to cut the casing open in order to discover why I couldn't unscrew the fourth. It was a slotted spanner.
I'd use my dremel to finish the slot that was only partially cut.
Or use the dremel to cut a slot in the end of a flat screwdriver.