The good news is that when i set up the ZX81 it burst into life for the first time in over 30 years. I attached it to a Decca Black & White portable television which itself is 37 years old! Sadly the oldest thing involved in the experiment was me!
And here is the program that was run to test the ZX81.
10 LET X=1
20 FOR X=1 TO 10
30 PRINT X
40 NEXT X
No 'HELLO WORLD' here!, maybe next time.
I ordered a couple of double sided edge connectors from Maplin Electronics to complete the construction of the extender board. These should be delivered in a few days. I need these before i can connect the extender board and I/O board to the ZX81 and perform some tests.