how do i remove the drum from the tub on hoover nhf 6127?

I am changing the rear tub assy (it developed a large hole). I got as far as removing the tub from the chassis and striping everything from it, but i couldnt get the drum out to put in the new tub. I tried "persuading" it using a rubber mallet but coulnt budge it. do I need to use a special puller or press? Ive patched the hole using glue but I fear it wont last too long, put it all back together and it still works which is an achivement in its self.