What does the area of the oven where the tank sits look like? Mine is like this:
There are round and oval pegs that align the tank and another round thing down in that reservoir that I assume allows the water to flow out of the tank. Neither of them seem to come off easily and don't look exactly like your photo, but I know there are multiple CSO models. Mine is one of the older ones (no steam clean button, no drain on the back)