how to smoothen the focusing ring of legacy lenses?

Hi

I've just bought some legacy konica glass to use with my NEX 7 and I have a little problem with the 57 / 1.2:

the focusing ring is mostly ok, but when I want to turn it just slightly, I feel some friction and the movement is not as precise as I'd like it to be.

Is there a way to smoothen its operation? what can be done?
I'd be happy with it anyway, just asking.

thanks