Hello 
Is it the motor that is making a distorted noise? If so, maybe some dust has made its way in. I'm from the UK and we don't have these bissell cleaners, but from a point of view of someone who has actually watched scientific reviews of cleaners like this I 'know' they're pretty bad. This isn't your fault though and I forgive you
I see the plastic that's coming off. It looks to be part of something to lift the brushroll off the ground when idle? You looked it up anyway so I think it might be that as well.
I've seen a series of videos on YouTube of someone who has this series of cleaner but it's not the turbo version and it's in blue, and the motor is very amplified. It started when they were attempting to do a full house clean with it. IS this the sort of sound you're talking about?
I'd really love to help but I'm not someone who strips down vacuums or anything so I'm really sorry, anyhow I'm still quite interested
