When I bought my 1997 cavalier it did not have any problems with the speedometer.  It didn't come with a radio, so I bought a sony cd player to put in it. I had my brother to install it and then my speedometer stopped working.  I changed the cd player with a sanyo cd player and it started working again.  Later on, the speedometer stopped again.  Now, the cd player isn't latched in so it jiggles.  I started playing with it and I noticed that when I pressed down on the top of the cd player my speedometer started working again like nothing was wrong with it. When I pressed up on the bottom of the cd player my speedometer stopped working once again.  What is the problem?  Is it the cd player or a cable that touches the wires? Or is it the speedometer itself or I'm just going crazy?  Please help!
 
The only times i have had any problems with a speedometer my tranny went not too long after, and now the count is; 3 Rs trannys, and 4 Z-24 trannys. if it's the same problem i had, I'm sorry it's your tranny
 
One question then if it is my tranny then how come it works and don't work according  to the way I move my cd player?