Once in a while, the Kx ta824 goes dead. If I unplug it and replug it in, it usually doesn't help. If I plug it into a long extension cord, and then to another outlet on a different circuit, it comes back. I have had the outlet replaced, tested, and it checks out fine, but this still happens every couple of months. Any ideas?

I'm assuming you've ruled out the outlet and made sure something is not just tripping a circuit breaker. If so, there was a sizable batch of 824's made with defective power supplies a few years ago. It's possible that might be your problem as it causes units to go dead then come back up intermittently.

Call Panasonic tech support and tell them you've got an 824 with a power supply that's "going in and out". You'll be asked for its serial number to determine if it was one of the affected units -- if so, they'll provide a replacement power supply at no charge.

Good call TA in KC
Tech did reply and I gave them the Ser #. It is one of the affected units, and they are sending out a replacement.
Thanks !