My alligator lead was down to 1 strand so that has been fixed and elements within at least 4/5 displays are glowing....Sooo, rather than take a shotgun method to replacing parts I will try to nut it out.

I have some schematics but I need to print them out on A3 but don't have those facilities with me....From reading U5 RIOT is a suspect...

Ah, the old one-strand alligator lead will always cause problems.

From what I have heard on this forum, the RIOT chips are often suspect.