[Arran]

I've removed the 84 rectifier tube and i have lights on all the other tubes and the transformer does not smoke, get hot or crackle.

What's supposed to happen if the number 84 tube is removed? Could it be that I just need another 84 tube and not a transformer?

Thanks.

That means that there is a dead short or other heavy current load on the high voltage winding. It could be a faulty 84 tube but check between the B+ and B- with an ohm meter, low or no resistance means that something is shorted in the B+ circuits.
Regards
Arran