how can i fix my clothes dryer?? ?

We have a 6kg Simpon Clothes Dryer EZI and my partner took it apart to clean the dust build up.. When we put it back together and tested it , it worked for all of 5 seconds before the drum fell down a bit.. I wasn't with him when he took it apart so I am unsure if there needs to be a screw in the inside in the middle to hold it together?? Hope this makes sense as I am unsure if thats the right name for what you put the clothes in (drum)??