I have to really slam my hood to get the mechanism to catch. There does not appear to be any upward adjustment on the mechanism so how do I fix the problem?

 

There are 2 hood bumpers toward the outside of the radiator support. You can use a 1/2" wrench to loosen up the jam nuts, then a phillips screw driver to screw the hood bumpers down a bit. If that does not fix it, you have larger issues & I'd need to see it to give more info. Some pictures of the front of the car from several angles may help us give you better info.

 

Some history - I am totally new to the A body. I have restored nothing but F bodies all my life and their hood latch is totally different and very easy to adjust. I have the hood bumpers set for perfect fit against the fenders - just seems very strange GM didnt make the hood latch easily height adjustable. I can move it left & right and of course the hood part itself won't move. Car probably has front end damage history. I am thinking about attaching my engine hoist to the mechanism and lifting the front end to see if I can get 1/4" higher just by bending the rad support?