AIWA CX-NA888 RH cassette door will not latch?

I recently inherited this stereo. I like the sound, but the right hand cassette door will not latch to stay closed. I examined the latch closely, and it does not appear to be broken, i.e., it looks exactly like the left hand one. However, there is a small square hole at the back where a lug fits as you close the door. the right hand hole appears to have something in it (black), and I wonder if it is some sort of switch. There is nothing in the hole on the left hand. This black item may be restricting the door from closing all the way. I tried to move it aside, and it moves, but it is attached to something.
Can anyone help me with this?