These are the pictures of a Chamberlain HD600DS. I was able to track the wall mounted transponder to the two wires at the left. Since there is no polarity, it was easy to push them through together with the wall mounted transponder. Had a couple of issues weeks after where my garage door was opening by itself. Uninstalled the IFTTT integration, changed the Sensor Threshold to 15 (as indicated by Garadget) and so far, the problem was solved. See pictures for the wiring setup.