Wltoys 12428b (part 4; fixing steering)

Note there's a deal of thinking out loud here, I'm no expert on any of this.  So I pulled the transmitter apart again.  There are 3 wires coming from the steering or "wheel";  Red, Black and White (see below). 

With the device powered off, i disconnected the wheel from the PCB using the connector.  Then I inserted thin jumper leads into the (female) wheel side of the connector, variously attached them to my multi-meter and applied steering inputs as follows:

1. Connected to Red and Black, resistance decreases as steering is applied counter clockwise.  No change to resistance as steering is applied clockwise.
2. Connected to White and Black, resistance decreases as steering is applied clockwise.  No change to resistance as steering is applied clockwise.

My guess is that Black is Vcc and the wheel itself turns a potentiometer.  So my theory is that i should be able to swap the Red and White cables over and we're good to go...fast forward an hour or so, and YES!!!  

It turns out you can remove the potentiometer from the transmitter and it makes it much easier to work on.  Just unscrew the nearby mount for the trigger in order to access all the screws.  At any rate, with the pot out on the bench, it's pretty easy to see what has to happen.  I noted the OEM setup in case i needed to revert it

PS: Thanks to tk on #taslug for the tips and Tribesmanjohn for the Oscilliscope which it turned out i didn't need ;) but it's been much fun playing with it anyhow.

PPS: We have two of these cars and on the 2nd one the remote was fine.. go figure!