Hello Rex and welcome! Tear down is pretty easy on your Mark 5. You need to unhook that cable and undo two bolts and it should slide right apart. Unless the drive shaft is rusted into the power head. Some times that happens. Putting it back together and doing your best to seal it up is a real problem with this motor. The cable runs through an aluminum tube and usually it goes in and out good, unless it is frayed out to much. When I put mine back together I turn the motor upside down in it’s stand. Aligning the aluminum tube and the drive shaft at the same time can be a bugger. Remember to grease the splines where they go into the power head, use cornhead , lubraplate or a “OO” grade grease in gear case, and drain the water out often. You will be hard pressed to get it sealed up good enough to keep the water out. (you can prove me wrong I been wrong before) I just finished mine this spring. Good running motors but those gear cases can soak up a bunch of dollars real quick.
Don’t know what screw you are referring too.
dale
