Agree with coils on the fix for the loose cover. Same way I do it.
Cresent wrench, and tweak it just a little at the flat section at the base.
When you say the trigger pin came out of the side hole I gather you're talking about the right side.
I normally hit the 'X', and 'Y' shaped pin hole stiffener bends in the center of the grooves with a screwdriver to push them in just a tad.
Here you can see the crease created by the screwdriver/ hammer method.
Works great, and less impact on the paint/ finish than the socket method.
Congrats on a successful build