I'm 200+ primers into this thing and can say this:
Unless i relese the handle at the bottom and let it flip up, the thing does'nt feed primers much all.
And sometimes it does'nt despite. Then i have to knock the primer tray with a knuckle to feed.
It works like a charm when it feeds, but i suspect it will be a dust collector on a shady shelf in no time flat and i will use my good old trusty Lee hand primer for the next 30 years (it's from 1986).
I read the manual, i saw the youtube films and still it operates so fine and elegantly that there is not enough disturbance to trickle primers from the tray by itself.