Hi. The radio club at my local MakerSpace has a donated TS-570D. It was working fine when we first started using it. Last fall, it would sometimes "lose its tune" (SWR would suddenly jump) in mid-transmit, and in one case the unit spontaneously powered down. In fact, that was the last time it was used, around last November or so. We recently moved the entire rig, and I am in the process of getting the new system and antenna up and running. Here is a description of the current behavior, in a nutshell. I have duplicated this repeatedly. To narrow down the issue I removed both the external LDG tuner as well as the antenna - now using a rated 50 Ohm load. 1) When in CW mode, it will not transmit. Pressing the SEND button does nothing. Stays receiving. 2) When in SSB mode, it will not transmit. Pressing the PTT on the mike does nothing. Stays receiving. 3) When holding the AT TUNE button to tune, it appears to tune ... and stays stuck in TX mode! Talking into the mike is continually transmitted, and changing the power setting changes the output power, and the SWR seems to read an appropriate value. There seems to be no way out of this stuck TX mode, except to cycle the power. It seems like the transmitter is likely working, and the issue is some aspect of the control circuitry. I found a copy of the service manual. While I am not afraid of attempting repairs, I am not an expert on radio/RF stuff. But I am a EE, and I can find my way around a schematic. Any advice is appreciated.