Zenith AM-FM G725 - A825

[DavGoodlin]

Putting down 1950 G725, I had a few ideas on the 1955 T825. Without changing parts other than wax caps and electrolytics, the 12AT7 socket ended up being the issue.

Numerous applications of Deoxit and tube swaps did not make any difference. I started pushing on tube socket pins with a chopstick, a useful tool for tuning coils and prodding suspected bad connections. Once I pushed the grid pins 2 and 7, AM and FM began to work. I replaced the 9 pin socket with a black molded NOS type. All bands work great now as I had done all but the RF alignments.

What I cannot understand is how and otherwise quality brown molded socket can fail? Is this an issue of corroded pins, not responding to chemicals, springing or reaming out with fine wire? Is it carbon-tracked?