Well I just went and fiddled with the tube a bit more and saw some bubbles come out, floating to the surface of my jug. Filled with hope, I decided to turn on the machine one more time to see if the auto refill would pull fresh water in, and it did!

Still not sure why/how, so would love comments and any wisdom you have for future use.

Kevin

See Can a rotary pump suck up from a bucket? and Do most plumb-in machines require external pressure? As I noted earlier in this thread, you need a check valve:


Ball-type check valve assures water flows only one direction