That does seem strange….double check to make sure you are really testing the correct pins.
Also, check for continuity between pin 23 and the center pin of the depth pot. If the center pin of the depth pot is changing, pin 23 should be changing too, unless that connection is broken somehow.
You also may want to use a ground point on the PCB…like the point where the grounding wire is soldered…just in case the ground lug isn’t making good connection with the chassis.
-Brach