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 double barreled shotgun found on the second floor of the main house, after you receive the scorpion key, or wait awhile and repair the broken handgun found in the trailer once you get outside.

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! Now you can use both broken weapons!
I hope that this guide was helpful, in it's simplicity.
/ER