1992 Toyota Corolla Speedometer - Odometer quit working. Ho

My speedometer and odometer quit working at the same time. The cable connecting the speedometer to the transmission has 2 sections. I reached under the dash to feel if the cable was connected and seems to be okay. While I was driving, I reached under the dash to see if moving the cable while driving would help. This didn't solve the problem, but I did notice as I jerked the cable, while driving, it would cause the speedometer to jump very slightly and immediately back to zero again. I figure this may indicate the connection to the speedometer is in working condition. So perhaps the problem is either at the transmission connection, where cable connects to the transmission. Either at the cable end or inside the transmission. Or perhaps the problem is where the 2 different cables connect to each other. How do I diagnose where the problem is? Thanks.