i believe the open switch is simply dependent on pressure against the circuit in the small hole. all you do is press a round peg into the hole and it presses the 2 sheets together and the disc ejects.
the purpose of the 2 pegs in the drive slot are to sense when a disc has been inserted into the drive. it then activates the loading mechainsm. they are supposed to be there
i havent made anything for mine yet!!!
~mike