[samjmann]

Thanks for the helpful replies. I could put a 1ohm resistor in series with one of the fuses and measure the AC volts across it, this would give me some idea. All that is being fed is a small graphic equaliser. The existing transformer is much the same size as the proposed replacement. All that's wrong with the original is the internal thermal fuse in the primary is open circuit. The unit does work when on the 220V setting when i used it with a variac.
For some reason the fuse is just in the 240v primary winding.

Regards, SJM.