Transplanted the volume control slider from the TK 141 to the TK 146.
Now the TK 146 volume is working very well, cannot get it to go bad, looks like it is fixed, time will tell
Did quick microphone recording test, worked well. With the case removed from the chassis in order to do microphone recording, you have to manually pull back and hold the microphone selector slider switch near rear of the main board.
With the case fitted, to access the microphone DIN socket there is a spring loaded cover plate over the socket that has to be pulled back to insert the microphone connector, this also pulls back the microphone selector switch.
David