Re: tension bolt for motor ?
Don't know if your engine has power trim and tilt or not,but there is a trim point at which the steering will attain a neutral pull as long as the trim tab is adjusted correctly.An engine without power trim/tilt has a transom bracket rod that can be adjusted to the most suitable hole.Not to question your tab adjustment but you didn't mention which way you moved it so I'll ask.......did you make sure and adjust it where the trailing end of the tab is moved toward the side that the boat pulls to?
No tension adjustment that I am aware of,but the fact that it will move freely is a good sign that the teleflex cable and the tilt tube is in non-corroded condition.Later model OMC including my 96' incorporate a 'no feedback' steering gear box for that very reason.