EuroSystem/EuroStep I/O board

[robertpearce4]

Hi Guys,
The Controller Card (Mint Card) for my Triac VMC has suffered bad corrosion damage from the battery back-up despite being recently replaced and not leaking.
It has eaten into the track for the adjacent RS232 line buffer/drivers U16 & U17 (SN75155D).
I have tried to use the serial data pins on the rear 96 way connector but still don't get comms. I'm not sure if these pins use the same driver chips? Does anyone know if there is any circuit diagrams or track layouts available for these cards? Failing this would anyone know if repair or replacements cards (1990 Optimised Controls LTD) are available. The card is a D281 Issue 5 with a Mint 3.28 v1.6h/S-JDS EPROM fitted.
I have tried to follow what track is left but there are gaps in my connection info where the track and pads were totally missing. Being a 4 layer board this is very tricky task.
Thanks
Robert