Trim Question

I have two ox66 250 salt water engines in my boat. When I push the trim up button, both start to come up, however, one of them comes up slower than the other one, and when I push the down buttom, the same happen, one comes down slower. Should I bleed it to check for air?' How can check the oil level?

Thanks

[boats.net]

With motor at full tilt up, fill with trim fluid until oil runs out fill hole.