HAM Kenwood TS-430 / X Frequency Display Problem Diagnostic

Amateur Radio TS-43X Frequency Display Diagnostic to solve problem with indicated VFO frequency errors.

This is a diagnostic journey on the rarer Kenwood TS-43X HF Amateur transceiver. The TS-430 & virtually identical TS-43X is an iconic HF transceiver from the mid-1980s.

The radio has in recently developed this VFO Display issue that has left the radio completely useless.
This is a common problem with this model, and with many similar models from the same era.

Following this First PART diagnostic project, the VFO Frequency Display has indicated that it will work immediately for 15-30 seconds then lock up. Further examination of possible causes will follow in PART 2 at a later date.