How to get cats to use a recently abandoned Litterbox

We have 2 cats and two litter boxes. One box upstairs and one downstairs.

Up until recently, my two cats would use both about the same.

I then noticed that the downstairs box was not getting much "action" anymore.

I traced it to the fact that the door on the front (both boxes are exactly the same... they have a lid and a plastic door on the front) wasn't opening properly. I'm speculating that if they thought they couldnt get out, they stopped using it.

Well I fixed the door and it moves freely now, but the cats still are not using it as much.

How can I tell them that the door is fixed and they are safe to go inside again?

There is a product called "Cat Attract" which you can mix with the litter. It works well when trying to get cats to start using the litter box again.

You know the door now works but the cats may not, and there's not really any way to tell a cat something like that. Try taking the door off completely, or even the top cover.

We use covered litter boxes but remove the swinging door. Give that a try - then, because they use the door, if you even want it back on, put it back on in a couple of weeks once they're using the box again.

Laurie