Wow...that's a tough one due to the fact that you are SO close to hatch date. Generally you do not want to touch and handle eggs or the broody much, especially at day 19 because you can interfere with the hatching process those last couple of days. At least that's what I've been told.
I too was close to hatch, and I have over handled a broody before and caused her to abandon the project, so I am leery of being over aggressive again. I had my daughter hold the broody, then I gently dry paper toweled off the good eggs (which mostly were okay clean) and pulled out the bad eggs and soiled nesting material (which is where most of the smell was coming from). I then filled in with good nesting material, replaced the eggs, replaced the hen, spending as little time as possible and little disruption as possible. I did not attempt to clean the bird up (she actually amazingly didn't look that bad).
Anyway, my 2 cents and personal experience.
Good Luck. Post what you do, how it went, and what hatches. I'd like to learn from your experience as well.
Lady of McCamley