really oh well i got it fix, the box i think was glue in so i destroyed the couper box lucky i had another coupler box laying around.
You are supposed to remove the coupler....not the whole box, check this out:
Paint may be holding it on.
http://www.tcsdcc.com/Customer_Content/Installation_Pictures/HO_Scale/Athearn/SD60/Genesis%20SD60.html
Take Care!
Frank
i just pick up the athearn RTR sd60 engine. i'm going to add a decoder to it but how do i remove the front coupler box? i remove the screw that holding it and lighty pulled but nothing. i remove the back coupler box and it was easy. i trying not to pull too hard not break the front of the engine.