It looks like your issue is very similar to a problem I had with my new to me 1999 sailfish this season. It looks like you have two different steering setups on the motor, the old and the new SeaStar system and they do not work well together. I only found this out after the piston fell off and nearly lost all steering in the river my boat is in, ended up having to pull the boat and address the issue. I even called SeaStar technical support and sent them photos and they were of no help. Here is the link to what I had to do.
viewtopic.php?f=2&t=23166&p=141412&hilit=272+steering#p141412
There could be some other problems, like if where the motor hinges, if its getting sticky, but removing the current steering arm will tell you if they are free or not. Mine were fine. The new linkage worked perfect and the steering is very tight and the piston is attached as it should be. The SeaStar part number I bought was HO6001.
Page 153 and 154 on the following link shows how your steering was most likely from the factory. Looks like someone replaced the steering cylinder with the new style and jammed it together. Took me a few days of endless internet searching to figure this out myself, but I bet your current cylinder is binding on something. I was almost ready to buy a new steering system and start from scratch, but the HO6001 part saved the day for me.
https://www.jamestowndistributors.com/u ... rStrg(v4_0)Parts.pdf
Looks like there is a hose clamp in one of your photos holding the steering cylinder up, if that is the case I bet that is the cause for the hard steering. Hopefully this all helps and I didn't confuse you more. Let me know if I can help anymore, boat is an hour away but I messed with it so much I have a good memory of it.
Andrew