Generally, if I make any sort of functional change to any given radio - dropping resistor, dropping capacitor, whatever, a 3 x 5 card will go under the chassis with such notes on it. I am not above using an etcher as well to make sure that something really important is not lost over time.

Stuff "below the chassis" has its significant advantages but unless explained becomes a mystery to the next user.

Peter Wieck
Melrose Park, PA