Just a quick update, 2 trace links soldered, switched on & held my breath..
Incredible! What a surprise to see that lovely boot screen after so many years. This a500 was bought by my father back in 92, and he loved this machine. Just wish he were around to see this working again, I'm sure he would be very happy.. just as I am. I will press on now, and continue to restore this old girl back to her former glory, just hope she works when it's all back together!!
Thanks for all the help and advice here, much appreciated 
I will continue to post some progress when I have the time.
Michael T
Nice work,you need to neutralize that leakage with vinegar or some such then clean it well with isopropyl alcohol or it will continue eating traces.
you can de-solder any chip and replace it on that board, all common ttl parts(if you have the skill).
