I took the ugly carpet off the back step.
And found that the lintel had rotted out.
The boards behind have a small amount of surface damage. Two thirds of the lintel (sill) is solid enough.
The horns extend under the frame and under the stucco.
I have a board big enough to cut the sill out in one peice.
All ways to fix this I have found are flawed.
Cut full sill with horns and slide straight in: blocked by concrete step.
Full sill and cut bottom of frame, drop down, replace cut outs: blocked by stucco over horns.
Same with short horns: not bad but short horns will need hiding.
Pull entire door and rehang after normal assembly: way too much work and extra damage.
Make full sill, chop six inches from hinge end, slide in short bit, force long part in at an angle: difficult to align seam. no access to shim under after assembly.
Cut old sill straight just behind rot, make two part partial sill like above. Insert small then large, screw to old sill to align parts: finicky, still no support under, lots of seams to hide.
PS
Cut out old wood fairly even. Used router to cut neat line across middle. Finished with chisels.
Chipped concrete to remove cups so water drains. No fill or sealant under lintel.
Cut replacement board with wings in two parts. Forced it into place. Screwed down solid. Filled and sanded even with old lintel board.
Cleaned off step and painted with leftover step paint.
