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.
Damn, I didn’t even think of that. It would be ruining a good screwdriver, but you could just use an old worn flat-head drill bit.
Good call, either way.