The baffles are attached by 2 long screws, which are most likely laying in the bottom of the cabinet if they are not still attached to the baffle. If the screws wore thru the drum, larger washers will need to be placed over the screw heads to cover the wallowed out mounting hole. To get to the back of the drum to attach the baffles is easy, simply remove the top panel. There are 3 screws in back, as hown by the following diagram, to allow the top to come off (#2). If you need to hunt for the screws, remove the lower panel and grab a flashlight Diagram of your dryer
Any further research on this dryer can be found in the Duet Dryer Manual on the Whirlpool Forum.