For maintenance questions talk to Karsten Schafer in Jet Aviation, Hanover, what he doesn't know about Astra's isn't worth knowing. (also Christian Kinitz) He helped me out several times when I was looking at Astra SPX's for a client.
I don't think there is anyone left in the UK with experience on the Astra's although I think Northern Executive used to manage a Westwind.
Mike Echo