Bell South Answering Machine (HAC) 3890Z?

This is an old answering machine but it has been working fine til just recently. It hasn't charged the phone for a long time but the answering machine was ok. Now, when someone calls and the machine comes on you can hear"Please leave a msg after the tone" but you can't hear the person on the other end. Please tell me this is fixable. This machine has always been so easy to operate that even I could do it.