The method to build up a model is to take it a step at a time.  The first thing to get working is a single drop. The part should hit, bounce up and fall down and hit again and the bounce should get smaller and smaller until there are no more bounces. Can you get that first model working? 

I tried and there are problems even in this simplest model. Do you see after impact, the first bounce looks great, but then the part starts shuttling back and forth between the ends and seems to be gaining energy, not losing energy.  This model has zero damping. This has the acceleration constant during the entire time.