Coupler height issue on new Pennsylvania Broadway heavyweight vs RPO

An image of the mismatch? Does the engine coupler match the rest of your fleet height wise? If so and the RPO matches the engine I'd focus my attention on the first passenger car for modification.

Thanks for the response. I moved the car around and last position was behind the observation car.  The coupler height varied from even to slightly below and above.  Regardless the RPO car couplers on both ends eventually release even attached at the end with weight of car itself. Simply going to call Lionel as visually cannot see a cause and this car is new. 

Does it have the thumbtack or the hidden tab?  If it is the tab, I'd bet it isn't able to return enough.

Rpo is thumbtack 

Passenger cars are hidden tab