Having studied the issue further, I've figured out some additional details.
First and foremost, the problem isn't actually a "cold" solder joint.The issue is that when the connector was originally soldered to the board, the 40 contact pins weren't touching the board, they were suspended slightly above the board . . .
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Thanks for the new information, Jon.
Your discovery is very reassuring. I found myself cutting 'way back on the length of time I had my SDS100 running and avoiding hot rooms and automobile interiors in hopes of keeping my newly repaired solder joints intact. Here's hoping that the Uniden repair people correctly fixed my J401 problem, and I don't experience a recurrence. If it dies again, I'm shipping it to you for repairs!
In the meantime, please keep us posted regarding the $64,000 question about whether or not that issue was addressed in newer production versions of the SDS100.
Glad you're around, Jon! Thanks.
-Johnnie (KC5IGH)