Issues with Blackhawk 50 cal.

We have just started using our new .50 cal Blackhawk markers, but the paint does not consistently drop into place.  They are getting "stuck" in both the neck of the new hoppers and also in the elbow section.   Our maintenance person reamed out the opening in the neck of the hopper and that has solved that issue, but the balls are still getting stuck in the elbow section.   Any ideas on how to remedy this?