Don't get in a broken boat!
Why does this argument continue? I just heard it last week again. "Well we took it to the keys and it worked fine", only possible reply was given "Well your an idiot!". Why in the world would somebody risk their life and the life of others on something that they know is unsafe? Do you think my friend told everybody that went out on the boat- "oh and by the way this boat is visibly breaking in half, it is completely unsafe, we knew it before we towed it 400 miles to take you all out into open water"? I'm betting the answer is nope.
Did you guys see the youtube video if the guys on the bass boat? The motor came off at speed. Did it fall off the back and sink in the drink? No because your motor still has steering and control cables hooked to it. It flipped right up into the boat, full throttle hitting the guys in the head. One of them's melons was inches from the prop spinning at who knows rpm after it left the water.
Fix it or sell it and disclose the truth, and yes I believe fully the guy you bought it from knew it's condition. Why did you think you got a boat, motor, trailer for $1,500?
But above all don't ignore it and just hope everything will be fine.