[jspatz1]

From our experience and from the description of your problem, my guess would be that you are not guiding the disc stack closely enough. The stack needs to be contained so closely that the discs are not capable of tilting and nesting any more than they do when stacked vertically.

Special attention must be paid to how the exit slot controls the bottom two discs. The lower edge of the exit slot needs to be exactly the height of one disc (1.5"), or even lower if it is flexible. The second disc is prevented from tilting forward in front of the bottom disc only by this lip, so it must be right. Once again it must fit the diameter closely. Leaving a sharp, rough, or rubber edge on this lip helps in retaining the second disc.

The bottom disc must be prevented from being shaken or jarred forward (through the exit slot) when other discs are on top of it. Some additional friction in a limited area at this location is helpful. The width of the exit slot can be reduced so there is some slight interference with the edges of the disc when it exits, just enough to prevent it from exiting forward prematurely.

The height of the plunger which pushes the bottom disc is critical so that it does not attempt to go above or below the rounded profile of the edge of the disc. We push on the disc about 3/8" above the shooting surface. If you are pulling the disc from the inside, try to reach up into the interior about 3/8" rather than pulling on the lower edge. Of course a pulling hook must somehow go away before the trailing edge of the disc passes over it.

It is best if the entire feeding and shooting surface is a smooth, solid surface. Bad things happen when the circular discs can tilt slightly in grooves or rails. Be sure that debris can not accumulate in the feeding area. The slight tilt of a disc resting on a piece of debris can mess things up.