Help! noob in over his head with new ("used") Tenlog TL-D3-pro setup :-(

[minneapolis-matt]

dang. On the one hand I am very happy that after speaking to amazon about the dead E1 extruder they have sent me an $80 gift card to cover the expense of the $40 extruder replacement. On the other hand I am getting very pessimistic and uneasy about the noisy X-axis homing collisions. It is as if there is no photo sensor functionality at all for the X-axis limit detection and the troubleshooting guide and manual only seem to recommend re-checking the cable connections...which unfortunately seem nearly idiot proof. The long set of cables would almost certainly need to go to the x-axis as this bridge has a large range of vertical movement and the shorter cables would need to serve for the Z-axis as these connections do not have any range of movement to accommodate. There is really nothing else to get wrong on the connections and if it did work with the cables switched not only would the cable labels be incorrect but there wouldn't be enough cable slack for the extruder bridge to move more than about 4 cm up or down and the z-axis base would be left with a comically large 35 cm loop of cable draped over a fixed gap of about 3 cm at the gantry base. I can't definitively ID the X-axis limit photosensor or find a picture on the net but the picture below suggests the switch is the little "EE-SX6" module attached to the rail spool housing and if so I'm not sure what the arrows mean or how exactly it's supposed to work. Obviously there's nothing in the area that would move into the little interior pocket of the module so what determines the detection point? I'm frankly stymied as to how to troubleshoot this thing.