German,
Thank you for that excellent video. It was very informative. If pictures are worth 1000 words, videos are worth at least 1000000 words.
So it looks like your depth knob is not functioning properly. Please double check your solder joints on the depth pot and on pin 23 of the micro controller…re-flow them even if they look good. Also double check for solder bridges on both sides of the board, especially on the pins on that pot. While you have the board out of the chassis, turn it on and see if you still have this problem. It may be that a component’s lead is poking through the paper and shorting out on the back of one of the pots while it is installed in the chassis. Look carefully and make sure that’s not happening. While it’s out of the chassis try to slightly lift the pots off the board to ensure this isn’t happening.
Let me know what you find.
Good luck,
-Brach