Fire Brick Broken

My wife called and said one of the four fire bricks was cracked, and now in two pieces. It now won't say in place. She asked should she run the stove without one brick. I said lets not. Told her to replace all four. I know there are different materials used for these. I'm assuming they all will work, Any reason they won't work and I should look for the exact ones I have?

What do you think about running without one of the bricks?

your stove only has 4 fire bricks?

Yes, the Oslo has only 4 bricks in the back, and they should all be in place.
You can pick up bricks at your local hearth shop, menards or Ace hardware often has them. As long as it's firebrick, it will be fine.

Replace.

The place I am buying has a Quadrafire stove. There are 20 or so bricks on the floor and walls. 4 or 5 of them are cracked or broken. I know the previous owner fired it with broken bricks, probably didn't even know. Can you fire the stove with a broken brick? Probably. But its not the right thing to do and I'll be giving the stove at this place a complete cleanout and replace bricks before I fire. Tractor Supply Company also has firebricks, and I am told you can cut them with a tile saw if you can't find the exact size you need.

^ a lil crack is not a big deal as long as all the pieces are in place