Mod to fix or replace castles crappy ESC fan?

I have two MMM ESC's that when the fan runs makes it a zzzzzzz sound. I think a blade is rubbing something. I have broken so many fans on my RC's over they years (not on the MMM though). I wish there was a stronger model of fan.

Is it possible to fix the zzzzzz sound or should I not worry about it till after it breaks completely?

Fired "Frostbyte" up for a bash session this morning and it made its first tell tale sound of a failing fan grinding away. Uh oh......