I have only ever used duct tape on one appliance that gets used a couple of times a year and it isn't a vacuum cleaner but from a brand who make vacuums and also fit the poorest plastic imaginable when it comes to their expertise with a certain outdoor appliance.
My Karcher pressure washer.
The handle cracked the day I bought it. It was far too heavy to take back to the shop, so I just wrapped duct tape around the handle and that was more than 7 years ago. The duct tape is still there and keeps my hand from getting cut.
I think duct tape can be good for some things but mostly on parts that won't move on a vacuum cleaner.