brakes binding

[alf]

A friend has a problem where his brakes are binding.
prior to a track day last week ( new car) all was fine, but now, the brakes are binding.
He assures me that it is not "nipping up" here and there", it is constantly binding throughout the revolution.


2 things suggested so far.
1/ its down to brake dust. take of the wheels, clean off all the dust etc all will be fine.
2/ he needs to apply copper slip.

question is wher to apply the copper slip.
the brakes binding, must cause a drain on power.

any advice??