I am wondering if there could be an internal mechanical cause for the problem. Something restricting the vibratory movement, or something that isn't properly secured, allowing movement in a wrong direction?
I'm interested to see how this comes out. I have one of the new-style barrel loaders. It's in place on the layout, but I haven't tried to operate it because I don't have the accessory control panel and wiring in place. Hopefully it will work when I get it fully installed.