Do NOT use a wimpy Tamiya/molex connector on a brushless setup, that motor can pull 50+ amps.........It'll be toast..........Get some proper traxxas connectors and solder them on, then shrink wrap them. Those adapter connectors are really meant for charging your batts with a charger that has molex.

And if he didnt share with the buying public on e-bay that he changed them from stock to crap, then he owes you something............maybe a small partial refund.