Mine came with some plastic blocks that when inserted block some quarter holes. But I was one short and found that there are some spring loaded metal fingers on the bottom side of the coin mech. I used a small plastic "zip strip" to hold the last one away from the mechanism like the coins do if fed through. I put it around the finger and around an adjacent piece of metal, pulled it up tight and cut off the excess.
I don't recall if you can do it to all of them, if you don't have the plastic blocks, but I don't know why not.
Bill V