Try this
Though I am not extremely familiar with this exact model, I can give you some tricks for royals.(some will apply to older kirbys(505-LegendII))
1. Make sure everything is taken off the main motor unit that can be(i,e, head, handle, casings and trim.
2.If it doesn’t want to come off, don’t force it.
3. If when you get it all cleaned up and back together it doesn’t work, consult your local vac shop.
Hope I was of some help,
Avery