OK, so I was still having problems despite several attempts to update. I uninstalled GSX and Addon Manager and deleted (actually renamed and moved) the folders in Appdata, ProgramData and Addon Manager. When I restarted I got an error (see attached file). When launching P3Dv4.5 it said it couldn't find the airport directories and did I want to unload them - I said Yes.
I have installed Addon Manager 4.5.0.18, GSX 2.6.1.0 and SODE 1.6.4. I also have Charlotte, Dallas, Chicago, Hawaiian Vol 1, Honolulu, JFK v2, KLAX, Memphis and Vancouver installed. Of course I have many other addon (too numerous to list) but ask if you need to know about a specific one.
Obviously I have made a mistake somewhere in this process.
Any assistance would be appreciated.
Cheers
Harry