Motorola Walkie Talkies not talking with each other

I have a pair of Motorola T5920 Talkabouts that came in the same package many years ago. I today put in fresh AA batteries in each of them. They were both set to Channel 5, Interference Eliminator Code (EIC) 1. I got dead silence when speaking on one to the other. Having tried everything else, I pressed the Advanced Scanning button (Z mon), and while speaking in one radio, the other one scanned the frequencies. It locked on Ch. 19, IEC 1, and I could hear myself broadcast. I locked that scanning radio on Ch 19, EIC 1. So, now my radios can communicate two-way, but one is Ch 5, EIC 1 and the other is Ch 19, EIC 1.

This is a very temporary solution which will be forgotten within a week. I simply want my walkie talkies to work as they are supposed to (i.e.: both have the same channel and EIC). Anyone have any ideas?