[GT390]

correction, the first transformer is fed from two phases @ 240v = 415V each into 0v and 415V giving me no where to go to reduce the voltage on the taps, pretty strange getting a potential of 240v from the 0v tab to earth ! At least I have learnt something today, just because the transformer has a 0v tab, dont mean its connected to 0v

I guess I am going to have to take turns off the transformer, is there a post and or pictures of the proceedure ?

[Al_The_Man]

You mention this transformer is fed across two phases, this represents a 415 single phase transformer, the star or neutral is not used.
If you want to reduce the secondary, it is usually wound on last, if so you are in luck as you take turns off as needed, and you can calculate as a minimum that there will be around 1.5 to 2 turns/volt.
With a square lamination type it is a bit uglier than doing it on a toroid, but it is possible with care.
Al.