I"ve tried it many different ways, I can recovery spins left and right with Power on .  But Power off, in the P38L I can't stop the rotation  to the right by just using normal spin recovery technique.  Doesn't matter if I have combat trim on or off or how much out of trim the aircraft is.  I can always recovery from a left spin and with power off, never recovery from a right spin.  I've used different types of sticks and even just the mouse and keyboard for rudder control.   no dice.