I have a few reports of the MGA bonnet safety catch misbehaving. In some cases the bottom end of the catch arm may go too far forward and fall in front of the catch bar. Then you have to manually push the arm back behind the catch bar before the bonnet will close. In one case the arm moved so far forward as to get hooked underneath the bonnet latch platform, thereby preventing the bonnet from opening.

Photo above shows the spring loaded safety catch arm in the correct position. A little bump on the way down moves the arm rearward so it will snap forward underneath the catch bar. If the arm moves too far forward you should check the pivot pin and pivot holes for wear. You might otherwise adjust the bent stop tab(s) at front edge of the mounting bracket to hold the arm a little farther back.