Reliable Dropper Elevator

Most vertical dropper pipes have a comparator only at the bottom dropper, so what happens if no more items enter that dropper, but there are still items in the pipe? - They never reach the top and get stuck within! This design is a little bit bulkier, but it makes up with reliability- it's impossible to jam it, you could throw in 10 000 items and it will shoot out every single one of them, and a modular design so that you can make it as tall as you want.

I designed it for a lottery machine where it would have been unacceptable that some of the items could get lost in transfer.