The most important part of my previous post is to check and confirm the leads on your transformer by using the supplied info from the transformer supplier.
The color codes really do change. You could also confirm the taps by checking the turns ratios with a multimeter, there are tutorials on the web that explain the process.
Regarding balancing the heater circuit, you can use the supplied 5.3v circuit center tap, make an artificial center tap by adding 100ohm resistors to ground to the heater circuit OR add a “humdinger” pot (500ohm) between the heater leads to fine tune the 6.3 v circuit balance.
Merlin Blencowe’s comments on heater circuits: http://www.valvewizard.co.uk/heater.html