I don't know much but heres what I can suggest...
I don't know a lot about these but I can say that you should check the top fan and make sure that screwed on correctly. I had a Hoover Convertible with that problems and I broke into the motor and found the top fan was making a rattling noise and I had to simply screw it back on tightly because it was being spun but it was loose causing it to lose control flying around a little area with the top of the motor spinning around.