Leopard brushless loss of power
 

I'm running a tc02 evo with a leopard 3300kv combo. It's been working great. For the last few months on our tight carpet track, until last night. It initially felt as if the punch was turned down, then I started to feel lag between throttle and brake inputs. Then all power was lost. It would barely move. If I gun the throttle, it limps off and then finally the power comes about 2 seconds later. Revving the car off the ground, you'd think a knackered silver can was in it, takes a couple of seconds to spin up. Any idea what could be wrong?

any tips on how i can narrow down the problem to esc, motor etc?