What is the smell like? Is is a old smell, urine, a decomposing dog hair smell, worse?
Some on this site have mentioned using an ozone generator to neutralize smells, I caution on that as ozone can attack rubber and plastic, but some say it works.
Since you have cleaned the bag chamber, and hose, you may have to disassemble and clean out the air paths to and from and maybe including the motor. Spa Day!!
Another possibility. I bought a used machine that was so perfumy it smelled like a French Brothel. After cleaning and cleaning, I finally set it outside on the porch and let it run for about 30 minutes. This seemed to air it out and the smell is not as strong each time I use it.