Last night I was googling for a Build 509 install when I came across a blog which discussed stopping the automatic upgrade and downgrading from Build 600. It included a zip of Build 509. It turned out to be an installed copy of the folder. So this morning I tried what dusktrader suggested. I zipped my working copy on one VPS and transferred to the new VPS. It worked. Zorro connected and is online.

So the MT4 on my home computer upgraded to Build 600 automatically. But the one on the original VPS did not. The one at home is regularly started and stopped. So it may have occurred during a start-up.

FYI - Info on stopping the auto update…
http://4xtrader.net/mt4-build-600-why-you-should-not-update-it/

So problem solved for now. I guess I will test the new Builds as they come out until one works and then do a proper in tall then…or not.