radio reception

My 2003 Mercury Grand Marquis radio reception went out. I was driving ,went over a bump in a construction zone, and the radio became reception spotty. The next week was on a rough road and reception was restored. A few weeks later on another rough road, radio reception went out.

CD/Cassette Tape player work fine.

I pulled the radio out and the saw that the antenna connections were attached pushed them in to tighten -but the radio reception was still not working.

I pulled the connections cleaned them re-attached them - radio reception was still not working.

The Grand Marquis has a rear window radio antenna. I cleaned the connections, cleaned copper tabs . Radio reception was still not working.

Has anyone had a similar problem and was able to solve it? Please advise me how to do it.

Anyone have an idea I can try?

Thanks, Bill Christian