we currently have a system that works pretty well for us
check out our video of it working
here
(don't mind the music... we were bored and couldn't think of anything else)
but if you do want to see some more detail of it look at our CAD renders on our facebook page
here (hopefully that works for you...)
we basically went through our previous designs from hot shot and looked at what worked and what more often than not didnt work. we determined that picking balls up by pushing them from the back required too large of a radius and required us getting too low to the ground which led to us getting jammed up so we focused on finding a new method which didnt require us to have to get so low and thus our current design...
im sure you will find a mechanism that works for you!