If you want more crisper and louder modulation on AM, turn radio upside down and remove cover at the top right hand corner of radio you will see a varible that says (AM mod). Clockwise increases mod and counter clockwise decreases mod. You might want to use another radio on the same frequency so you can hear results. The radio that you are listening with needs no ant screwed in to it being that you are only listening.
I have done this and mine has loud crisp modulation. Remember, no compression on AM, you will find that it will muffle you on AM.
Do at your own risk.