The cabinet bottom sits in a routed channel that goes all the way around the lower cabinet.

You either have to remove the lip on the channel, replace the floor, and reinstall the lip using glue and brads, or you have to remove the front or back, cut the old bottom out, and slide a new one in.

Either way, I don't know of any sources to buy a new cabinet floor, you'll have to cut your own.

Ouch, that's a bummer. I believe someone has a video on YouTube of replacing the bottom. It's a big job and I have seen it seldom done well. I've passed on a couple good deals because the cab bottoms needed replacing. I can do it but I don't want to. Good luck. I'll see if I can find a link for you.

You could try a master cabinet maker.

looks like its a little bit of work good luck

I had the same problem. Pushed the bottom plate back into position using the weight of the game on the top of a card chair. Reglued the jointer piece from the top of the cabinet. So far so good-4 weeks. I guess it's always worth trying. Saves a load of work.

Post some pics. One of my games was doing that and I was able to inject wood glue along the seem with a plastic syringe. Then I used a few pipe clamps to hold it in place while it dried. It was very solid afterwards and never had any issues.