Removing screen to access mail

During the transition of mail personnel, our temporary mail person would place mail in the area between the screen and the decorative frame. Some days when returning from work there had been no mail or at least I thought. Some weeks later I received a letter stating that I had not cashed a check which had been mailed to me. I never remember recieving that check. I normally just leave the screen in place, but this year due to the cold weather I decided to put the window up. When placing the screen structure down to position, it seemed to jam. Not a had jam but almost as if it was hitting something soft...like mail? I Now have to get to whatever it is that is keeping the screen from going down completely. I am having a problem removing the screen structure which would give me space to insert a grabber. Please help. Thanks