The First Repair Kit
The first repair kit is accessible as soon as you have opened the dog door and can finally step outside.
Starting from the trailer door, head towards the house.
There, between the two staircases to the porch, there will be a metal sheet that can you rip of the wall.
In this crawl space there will be a box, break it and you can repair either the handgun found in the trailer, or wait awhile and repair the broken double barreled shotgun (not recomended since this requires the snake key, which you get quite far down the line).
The Second Repair Kit
The second repair kit is in Lucas' house in the yard...
Enter the keycard door, proceed up the stairs, past the TV room into the first tripwire room.
Proceed through this room and you will see this doorway...
There, on that cage there will be a mannequin head with a cap (It disappears after interacting with it, so my drawing will have to do).
Interact with the head, and pick up the repair kit! If you remembered to take the model shotgun from the attic in the main house, you can now repair the double barreled shotgun!
Written by Fenris.