I am trying to replace the brushes on a Philips vacuum cleaner motor. I can’t figure out how to remove the brush holder but I was able to extract the worn brush by prying back the restraining tabs at the end. Unfortunately, I cannot insert the new one as it is too long to fit the space between the holder and the cover plate at the end. 

The holder should be removable because the new brush comes with a new holder but I can’t find any way to do this without breaking it. There is a plastic insulating mount that holds it in place, and that in turn seems to be held by tabs in the metal frame. It doesn’t look like it is designed to be replaced. Can anyone help with this?