Managed to finish removing the corroded socket and install the replacement tonight but still have some work to do before my 500+ is fully working.
I reckon I need some finer grit sandpaper than I have to clean the feet on the Gary chip as I put it in and powered it up (just composite for now) and All I got was a flashing screen and an occasionally flashing Power Light (sort of dims to flash).
anyway here's some pics so far:
Half the socket gone, board mostly cleaned:
New Socket install (2x 24pin):
Gary Chip in socket to make sure it fits + battery area and for a quick but so far unsuccessful test:
One thing that does concern me is I popped a trace on the bottom of the mobo where it connects to a Gary socket pin and it pulled several centimetres off the board - I was able to solder it directly to the pin and gave it a coating of nail polish but am still unsure if that is enuf (time will tell i guess - might put up a pic tomorrow night).
I also tested all the socket pins with my multimeter to makes sure none of them where accidentally connected and got perfect results first time so happy with that.
If I cant fix this board I have discovered that getting hold of a Rev6a board is quite cheap from Europe and I should be able to transplant all the ECS chips and half the ram.
Amiga 1200 w/ KS1.3, ACA1220 16Mhz 128MB w/ RTC, 4GB CF-HDD, a1011 External FDD
Amiga 500 w/ KS1.3, 512k Chip-Ram, 512k Slow-Ram, 4MB Fast-Ram, FDD Boot Selector, HxC RevC SD Floppy Drive, a1010 External FDD
Commodore 64 w/ 1541 Ultimate-II inc Tape Adapter, JiffyDOS, 1541 Disk Drive, 1531 Datasette, C64 Flyer Net Modem, ZoomFloppy