[HWYSTR455]

If the windshield is more than 10 years old, it's not a 'good' windshield. It most likely has all kinds of spidering on it at night when oncoming cars' lights hit it. Once you replace it, you will go 'oh wow!', betcha a million.

But, to further diag this, where is the wire look like it's in 'bad shape' ? Where it exits the glass where the plug is? Maybe post a pic.

You may want to check the piece that bolts to the cowl, that the antenna plugs into. Make sure the connection is clean, and is not damaged in any way.

That part has an inside piece as well, the antenna 'cord' that goes to the back of the radio. Those get beat up over time, and replacing that may be all you need. Not always fun to replace, but it would eliminate that as a possible cause, and is inexpensive.

Finally, it could be the internals of the radio itself. If it's an OE one, and you want it to work, you could send it off to be restored, but that's not inexpensive, and even when done, it will still just be a 50 yo OE radio.

EDIT: Also check for the ground strap on the cowl that makes contact with the hood when closed. That actually acts kind of like an antenna too.
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