This looks great... a lot of work involved in what you are doing here!
Are you doing it from the Circuit diagrams or from a bare original PCB?

I'm interested in spare 2650a 's as well ... that's the worst thing about buying a non working zac... hoping your processor is not toast.

The only other issue I have is displays... but i'm going to do a set of boards using some off the shelf led's to fix this issue.

Great Effort... I know how long it took me to do the displays which are simple compared to this.

We have replacement display boards in the works as well. We are having custom made LEDs made to the exact specifications (sizes etc) as the originals in both sizes. This is a little way off at this stage however as the order qty for custom displays is HUGE!!!