TurboGrafx Controller repair - one button....

The down button on my turbopad refuses to work.
Randomly when turning the system on and off when switching games it suddenly worked fine.
Now it just wont work at all.

I've taken it apart and cleaned the rubber contacts with soapy water.
I've used rubbing alcohol to gently clean the PCB contacts, they look perfectly fine, same as the other contact pads for left, right and up.
The rest of the pcb looks fine as well.

I searched all last night to see if there were any common failure points on the controller but came up empty.
Any thoughts?
Trying to add some pics

 

The button thats giving me an issue is the contact pad next to the SWG white lettering

 

Try cleaning the pad on the controller with rubbing alcohol and a q-tip. As for the rubber pad, what I would do is get a piece of paper and then press down on each of the buttons and drag them a short distance. This will make the pads get better contact.

 

yeah i tried to clean the contact pad on the PCB with rubbing alcohol, it was pretty clean to begin with...not much dirt/residue on the qtip afterwards. i can give it another cleaning. I think the pad on the rubber is in ok shape, i can use the pad for the down button on any of the other directional spots on the PCB, so that rules out the rubber.
Only thing left is the PCB itself.

Using a scrap piece of wire I am able to activate the left, up and down buttons by connecting the ground and "activate" portions of the button on the PCB. But the down is not working.

Just so weird because while testing games the down button randomly worked fine, then i restarted and tried a different game and it went back to zero responsiveness. So i know there must be some life left in it somewhere!

 

There could be fault in the cable or even the controller port itself that prevents the D-Pad from fully working.

 

If there was a fault in the cable, nothing would work since multiple buttons are encoded via register and passed over few lines. It could be failing component on the board or a hairline crack on the circuit trace from down to the ic.

 

PC Engine controllers are multiplexed. If the fault were on the console or the controller cable, more than one button would fail.

The chip on the other side of the board is a 74xx157 (four 2 to 1 multiplexer units).

 

so after more tinkering... the 8pin DIN male end got stuck in the console when i tried to unplug the cable. 2 of the pins were broken and i guess were not actually connecting the controller and console. if i jam the male end back into the end of the cable, then put it back in the console it works!

So for now it works, but before I figured it out, i ordered two new controllers because i'd prefer to have at least 1 reliable controller.
Thanks for all the responses.