Well, 'tis no more.
No, it wasn't supposed to be spitting out red hot embers. It turns out the motor has burned out. Apparently because I haven't been washing the pre-motor filter (at three month intervals) or the exhaust filter (monthly).
I didn't even know they existed, let alone that they needed tender loving care!
I blame George. He sheds too much hair.
I'll read the manual before I use the next hoover.