PS2 controller port not working

I have a Fat PS2 and the controller port doesn't work. Tried 2 different controllers. Sometimes if I mess with the plug for a little bit it will start working. What could be the problem?

 

have you thought about replacing the I/O board

 

Controller port (only one?) or controller ports? If it is only one controller port, have you checked that the pins of the bad port all have good connectivity with the PCB? If you are able to verify the correct functionality of each individual pin (with the right meters), that would be even better.

If both do not work, have you checked that the flat cable is inserted properly and it is clamped down on both ends?

 

I took apart my PS2 and re-seated the cable. Works good now. Cable looks worn so I'm getting a replacement.