HI
For the well-known problem of the ON/OFF button that came out immediately after a few years of use, I did the same thing with the Swiss Farnell about 15 years ago with my FT847, always perfectly functional.
Difficult to disassemble the radio front to find the old defekt switch, not so obvious but I did it.
Having put the two contacts together immediately, I have not had any problems since that day.
Now the writing on the front keyboard is a little faded, otherwise everything is OK!
Instead for the Kenwood MC85 mic, unfortunately I can't find the small PTT/LOCK switches even at Farnell ...
73