Hi Big,
Can you post the manufacturers names? All HO locos recently manufactured
(AFIK) running on DC move forward with + voltage on the right rail.

I have an old Revell tank engine which was reversed from this, and had
to swap wires on the motor to be able to consist it. Kind of a ticky job,
but worked out OK. If you can get the shell off you can see how much
trouble it is to reverse the motor.