Yamaha DTXpress/DTXplorer/DTXtreme

Dennis,

The most likely problem is the foam has had it.  There is no harm in
taking it apart and having a look if its already broken.  Check for
broken wires and if it seems ok, find some foam to put in there.  From
memory, you just peel the rubber bit off to get inside.  The rubber
may be failing as well, though.

If you want to buy another (they aren't expensive) it depends where
you are.  In Europe, Thomann provide a good service and good prices. 
In the USA, Drumbalaya are probably the best bet.

Keith.