Does the rough opening for this door need to be reframed?
Now that I've seen the photos, it's clear to me that at least the jack studs should be replaced; fortunately, their replacement should be fairly easy. The one on the latch side could be replaced by a 4x4, but it should have a tiny "sill plate" attached to half its bottom end with contruction adhesive because otherwise it'll overhang the existing sill plate.

If you don't reframe at this point, you're going to have a hard time keeping fasteners (nails, screws) in place - especially in that left-side jack stud, which is so badly split &amp; weathered.