Hello Doug,
I will assume your bonnet is lined up and seats properly.
1) Make sure the bonnet catch slider moves easily.
2) The bonnet latch spring must have a constant pull on the bonnet latch slider. The slider will be pulled to the right. (Photo 4)
3) The guide plate is centered. It will be centered over the bonnet latch hole when it is in the open position. (Photo 3)
4) Adjusting the base plate to the left or right will align the striker pin over the guide plate and align the bonnet. (Photo 1)
5) Adjusting the striker pin length will determine how flush the bonnet will be with the shroud and how far down the pin will go into the latch. That adjustment is done by turning the striker clock or counter clock wise. The nut on the top of the threaded striker pin will set it in place. (Photo 2)
If the tip of the striker is at the correct length, seating down in the latch slider, then the spring is not pulling on the slider with enough pressure to lock it in place.
If the springs pressure is not letting the slider move, then the striker pin head is not below the latch enough.
When you push down on the bonnet, you should hear the latch make a click.
I would start with those items.
Maybe the head on the pin does not have a good lip for the latch to grab.
Maybe the base plate is not secure and moving.
Maybe the spring is not strong enough.
Maybe I'm too sexy for my shirt.
Let us know if any of these items help.
Cheers,
Roger