Kinki THR-1 repair update (100% fixed):
I was crazy about the lost of sound in right channel and thought it was the ALPS potentiometer all along but it was the relay all along, my unit is from 2017 and due to the use the mechanism of the relay lost strenght for 1 channel
Repair was very simple, desolder old relay, solder the new one, done.
If you ever encounter this problem with your Kinki where you lose right or left channel sound don't get alarmed and don't panick, it is probably the OMRON relay, a 4€ repair...