Yes it is normal for steering to be lighter one way and harder the other. You might try adjusting the little tab on motor and just above and behind prop.
I mounted my charger in the rear of boat by batteries. I cut a piece of pressure treated board a little larger than charger. Used washers as spacers and made charger about 1/4 in above board for air flow. Then mounted board to floor.
If you can you might drop motor 1 bolt hole on transom. If it is already all the way down might have to go to stainless prop.
Proud Member of Team Geezer
Charlie Weaver USN/ENC 1965-1979