No brakes?
 

Why does my brakes always not work when my esc gets a lil hot or even warm?

Is it on a 9918? I think it is the brake fade, you can send your controller to mike so he can replace it.

That's brake fade for sure. BK really had quite a problem with this. The only way to stop it is to keep the controller cooler, but sometimes that's not the easiest/best solution.

is it freee to replace?

A little off topic, but is there an easy way to take off the heatsink (I want to use a bigger one)? It seems like it is held on by either thermal tape or thermal epoxy. I don't to use too much force for fear of ripping off a few FETs.

I don't think the heatsink can be taken off easily, unless there's some kind of solvent out there that can dissolve the epoxy without harming any of the compnonents or PCB traces.