So on the top piece a few various things that I'd probably do to try and simplify the model would be to eliminate fragmented pieces and try to replace them with some larger surfaces, like for example here where there are 2 separate faces:




I deleted those and then constructed one big cylinder surface like this:



Then trim that bigger surface with the other part to get just one face for that outer side wall part:



Anything you can do like that to simplify the edge structure of the model and make for fewer junctures where there are many edges radiating out from the same spot will tend to help with filleting.

Here's another area with some extra edges that were left over from the seam area of the original revolved base model:



Those can be eliminated by deleting those little faces there, and then replicating the surfaces from an adjacent piece that did not have the original seam running through it over. I did that by using Copy/Paste to duplicate those other surfaces, then using Rotate with an angle of -360/9 to bring them over and then joined them in place.

Then another problematic thing for filleting is when you have 2 surfaces that come fairly close to being smooth to one another but actually meet in a shallow angle instead of being either distinctly sharp or fully smooth.

You've got a situation like that in this area here:



Those pieces are not smooth to one another, they meet in a shallow angle - anything that meets in an angle will then make for a more complex fillet juncture between them, and when the angle is particularly shallow the juncture gets hard to deal with because it becomes a kind of tiny slivery thing.

So you want to make that area either smooth or more distinctly sharp before trying to fillet the blades, one way to smooth it out is to select these edges here:



And then do a fillet of a fairly large radius (larger than you will use for the blades later) to make those spots actually smooth (here with radius = 0.5):



So with those tuneups in place it looks like the bottom part of the blades there will fillet ok now, there is still some difficulty with the top piece, I'll take a look there next.

I've attached the 3DM model file with the above adjustements made, it's only a fragment of your original model.

- Michael