I would think there's some corrosion behind the hinges on both surfaces.
Getting the media out of the hinge pivots might be difficult; stripping is probably better for them.
Whenever you separate door hinges from the body, photo or mark adjustment locations.
That will save you some hassle with reassembly & adjustment.
Plan on a fair amount of time removing media from crevices.
I had a paint rep who hated soda blasting, claiming it created a primer adhesion problem.
I would think a thorough cleaning & de-greasing would remedy that, but never had soda done.