These lines will leak some fluid. Cut the wire ties that hold them in place so you have enough room to lift them above the power steering pump. This will minimize the fluid loss, mostly a mess. Use a piece of wire to tie the lines high onto a fuel line or something else. Later on the bleeding.
Now, the nut spring back is a greater problem.You should be able to remove the cotter pin and clevis pin between the cable end and cylinder clevis, completely loosen the cable nut on the cable sheath and pull the steering cable out from the steering cylinder/valve assembly. If the cable core doesn't slide out easily, I think you've found your steering problem. You may need to force it out with a soft dead blow or lead hammer, or a wood block and hammer. If you have to force the cable out, there is corrosion or gunk fouling up the action of the steering valve. Try cleaning and polishing the cable core until it slides freely through the valve bore. Use mineral spirits or acetone and steel wool or fine sand paper to clean the cable. But do not use any kind of lube. Merc. eliminated the grease zerk for a reason. Replacement cable instructions state boldly: Do not lubricate.
If the cable pulls out easily by hand, remove the cotter pin and pin from the steering cyl., and steering arm/tiller and see if your drive swings freely, stop to stop both directions using your hand on the steering arm.
Then comment back with your findings.