Well I did fill the thing back up. I'm going to buy a new impeller. The bushing is missing (obviously broken off). So the impeller slides forward. It doesn't make that noise when I run it dry. It only happens when its got fluid; and glycol isn't enough to give the pump motor any problem (it made it with water last time I ran it too). In the meantime I'm testing. I've almost got the right charge inside. The TXV is better behaving now that I've added some charge. Its pulling down very quickly... In fact while I was adding charge it cut off and pumped down.

Not quite there with the charge yet, but getting close.