Time for a New Radio ?

[Charlie]

About four years ago I replaced the aging AM/FM radio on my boat. It has a CD player and a jack to plug in an MP3 player. About a year ago it started acting out. When I play a CD it is fine. MP3 no problem but when I use the FM radio it has this problem of cutting and fading. It will be fine for a while when I first turn it on and then after awhile it will start fading and then come back strong. My first thought was the antenna. I disconnected the antenna completely and the radio continued to get good FM reception but would cut and fade. It isn't an expensive radio and I am sure the ones you can get now for the same price are much better but I hate to throw out something if there is an easy fix. Anyone have any ideas or tests I should run?