It depends what model you have. I have the dometic 511 and the bowl is also china and the base portion is plastic. Maybe we have the same type. You stated the bowl came loose from the base. Actually the base is secured to the floor and the bowl is held in place with a large screw type clamp similar to a radiator hose clamp and is secured to the base. If we have the same type it is a two piece toilet, a bowl and a base. I would suggest you google the model and look at the schematic for a detailed diagram. The bowl and base are two sections and if it is just a loose bowl just remove the plastic cover and tighten the clamp. It suggests certain inch lbs and I do not remember what they are. Over tightning will intefere with your toilet possibly not holding water in the bowl.