Re: OMC controls
It depends, somewhat, on the age of them.
If they are side mounted, two bolts hold the controls to the side board. Once removed, you have access to the back of the control box.
There are more screws in the back that hold the case together.
Also, the handlle has a screw that must be removed. It is usually covered by a handle hub cover.
Be careful splitting the case. Watch closely how everything fits together. There is a check ball and spring in there that sometimes fly out.