Re: Steers hard to the left
When you are at your most used operating point (speed, trim setting, load distribution) taking your hand off the wheel should be a non-event. If not, move your trim tab rear end in the direction of the problem. Like if your boat steers to the starboard (right) move the rear of the tab to the right. The more, the more. Some say just a bit at a time. I say, max it out. If you went too far you can bring it back accordingly. Very well may be that you will leave it there if you are having the problem you say you have.
Correcting this should alleviate the hard steering to the left.
Mark