If this is the regular Bachmann Blue box then your exploded diagram is here: https://www.bachmanntrains.com/home-usa/dwg/dwgs/HO_GP40.pdf
If you have the DCC Equipped - Non-sound unit, then your exploded diagram is here: https://www.bachmanntrains.com/home-usa/dwg/dwgs/HO_GP40_DCC.pdf
VT Bob
If you have the DCC Equipped - Non-sound unit, then your exploded diagram is here: https://www.bachmanntrains.com/home-usa/dwg/dwgs/HO_GP40_DCC.pdf
VT Bob