UPDATE: Yes, it worked! Thanks so much for your help, Brad.
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Nice. I'll try your suggestion. Fingers crossed.
Personally I had not been able to find a source for the Casio brand, so I have tried 3 offbrand. The latest was one from EPtech Power Store through Walmart. It had the same issue as the previous ones from Amazon. All were listed as AD-12 for PX-310. All would not seat well enough to stay connected.