The timing crystal is what my problem was.
Easiest way to check it is to find a mate with a GTI, and do a quick swap. You will be able to rule it out - or in - just by starting the engine.
Use a GTI cystal. 8 and 16v use the same. Apparently.
If it is that, you may be able to source a cheap Lucas part - test it. The Lucas part never worked on mine - depsite G&S "testing" it, whilst the VAG sourced part worked perfectly.
Regards,
Tin