so i picked up these 2 atari joysticks when i bought a 7800 at a flea market. i assumed they would also work with the 2600, but when i tried them both, they only moved side to side, not front and back. since both joysticks do this, i assume that it isnt the joysticks. are these for the 7800? also, there is a compartment underneath, what is this for?