Can you post the model number please. If you find the rating plate on the vac the model number will be on there.
The part you need is it what the dust bag slides into?
Ok if its the part which the bag clip slides into then its called a support and you can get it from the link below.
As the bag come with the locking cover on them so they slide down that support and locks in place.
So if its the support you need you can get it from the above link. It will show you a picture of it anyway.
If you need anymore info just get back to me.
Ok click here to see the bags.
On the bags they have a plastic grid which slids down the support and locks into the vac.
I wonder if its that you mean. As the plastic holder is part of each bag. So when you get new bags it will come with the plastic frame on it already.