Filament detector wiring .... Hmm, somethings not right

Hello. Had a search first, but drew a blank. My Flashforge Creator Pro has been a workhorse, had many fixes, but still going strong. I would like to add a filament detector to the unit and I have 3d printed one. I cannot find the wiring for the connections. If you look on Ebay, you can find these detectors, and they show it connected using the picture I have attached here. But, that isn't my motherboard (from what I can see). From what I can deduce, the limit switches hold the signal wire to 5V (normally closed on the microswitch) and this goes to 0v when you press the microswitch). There is always a 10k resistor pulling the signal line to +5v. If I plug it in where the image shows, then the print will 'kinda' pause, but not properly. It also totally messes up the position of the print (bumps it to the right significantly). Any idea? Sailfish firmware is the latest one as far as I can see. Is there something that needs enabling? Any assistance would be great. Thanks.