I just passed this hurdle a couple weekends ago on my 98 Speedster. Steering was VERY tight, like "make a muscle to move the wheel" tight.
My "Bad Cable" was actually a snowball effect of several tight/dry/corroded fittings.
The large 7/8" nut @ the transom will carry a lot of corrosion on the inside. Mine was really a mess. Wire wheel and lube. I used some heavy grease inside when I reinstalled it to lock water out.
PB Blaster works well if it is locked up, as you mentioned. (and on Flame arrestor plate bolts... but that's a different story...) :ack: Steering cable assembly is all SAE as opposed to metric, btw.
First take apart EVERYTHING from the transom on back to the nozzles. The test is, when it is all unhooked, is the steering lighter? Mine was immediately better so I knew I was onto something.
The fix for me was to simply clean, polish, and lube the heck out of every single point in the steering assembly from the transom on back, and to get some lube into the terminal end of the cable by spraying while turning the steering hard over from side to side repeatedly. While I was at it I wire wheeled and reshot my steering nozzles as they were mostly corroded with a couple patches of paint left here and there. Make sure to use some loctite blue on the steering nozzle bolts when you reinstall them, if you do this.
My steering is now 95% of as new if I had to rate it. My 8 yr. old daughter can steer from hard over to hard over no problem.