Wayne, I cannot help you with a tech center, but wondered if you have been through all of the steps in section 15 of the Instruction Manual "Trouble Shooting"
In particular there is an interesting section on resetting the microprocessor and wondered if that might clear up some of the problems you are experiencing?
"If your transceiver seems to be malfunctioning, resetting the microprocessor to its default settings may resolve the problem. There are 2 levels of resetting the microprocessor of the TS-590SG transceiver: Partial Reset and Full Reset."
In addition there is a VFO Reset
"Perform a VFO Reset if a key or control does not function according to the instructions in this manual. The following data is NOT erased by performing a VFO Reset.
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Memory channel data
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Menusettings
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Antenna tuner preset data
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ANT 1/ ANT 2 selection data
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Frequency and mode data for the Auto Mode function
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Various adjustment setting values
?Instructions are on page 85 if you have not tried these
--
Jeff - NZ2S
JeffBanke