I replaced the 74s32 with a 74ls32 (the closest replacement I could get) and the machine didn’t leap beck into life.
Disappointed doesn’t come close.
I powered it of and on again and it didn’t. That’s a bit odd.
Out came the boards and chips were pressed into sockets. Power up again and Bingo! Off and on and still OK.
So here’s the question… Was it the keyboard adapter that caused it to fail or was it just coincidence? I’m not sure if I dare find out yet.