1) Loosen the packing gland nut.
2) Loosen and remove the four nuts between the transmission and coupling.
3) Push the shaft towards the stern separating it from the transmission.
4) Apply penetrating oil to the shaft and coupling with PB Blaster or Thrust. Do not use WD40 or Liquid Wrench these are NOT true penetrating oils. PB Blaster or a product called Thrust are incredible products. Apply to both the prop end of the coupling and the transmission end by sliding the shaft towards the stern tube.
5) Next align the shaft upright and remove the seizing wire and two bolts that lock the coupling to the shaft. Next fill the two bolt holes with PB Blaster, wait a few minutes for it to absorb into the holes and repeat a few times. By hitting both ends of the coupling, and the center where the holes are, with PB Blaster, you will get better Penetration than just wetting the prop end of the coupling. It's best to fill the cap with PB Blaster & then use a Q-tip or use an eye dropper for application.