Losi Xcelorin ESC + LRP X12 Motor Problem

[jmke]

Hello, thanks for reading this post!

I recently ran into an issue with the combo mentioned in the title;
the motor ran fine for a few battery packs; but now when I turn it on, the motor won't turn. If I recalibrate the ESC the motor will run as long as you apply throttle, as soon as you make it stop it won't start again.

Applying throttle has no effect on the motor, the ESC lights up to indicate full throttle/reverse; only when I manually "help" the motor to turn will it power up.

I've verified the power connections from ESC <> motor; changed the sensor cable; to no avail. The motor is brand new out of the box, anybody know what could be causing this?

Thanks in advance for your advice.