Note: Underneath the cartridge tray is a black trapezoid-shaped tab/lip (see marker). When properly assembled this tab/lip goes below the motherboard and shielding as seen here.
During reassembly, make sure you orient this tab underneath the motherboard in addition to orienting the tray on top. Failure to do so will bow the cartridge tray and place stress on the component, causing the cartridge spring mechanism to bind.
Disconnect the wire harnesses from the motherboard assembly:
Player 1
Player 2
Power
Make sure you remember where player 1 and player 2 cables are plugged in; do not mix them up. A good technique would be to write each title on a piece of tape and wrap them around the appropriate wire.
I have the Mario track and duck hunt game but when j plug in the remote it switches from super Mario to the track meet but I can't control the remote ?