replacing blades on mulcher chipper

[smokey]

I have a Carravachi Bio350 Mulcher chipper which is no longer produced. The mulcher blade set up is similar to Aussie Red roo mulchers and I suspect others. I need to replace 2 blades and the retainer. Do you need to press the drum together to get enough tension? I did not and now the blades feel loose. Has any out there had experience servicing this type of equipment?