NES top loader - controller port issues

[Kazia]

I have a NES top loader that's come across my path with what I can only assume are controller port or related IC issues. Games start and run just fine, but as soon as you plug in a controller (to either the 1st or 2nd port) and try to press buttons the issues start...

Here's the scoop on the buttons:

When you plug in a controller it automatically acts as though the Start button was pressed.

Up, Down, Left, Right = seem to work just fine.

Start = seems to work just fine.

Select = doesn't work at all.

A / B = TOTALLY freak out. On occasion will actually act as A / B. Frequently act as though I'm pressing Start. Sometimes move my character left or right as well. Will often do a combination of Start, A / B, plus moving my character.

I tried 2 different controllers in both controller ports and got the same issues. Both controllers are known to be working, so it has to be something within the system.

Unfortunately, someone tried to do a repair on this system already. It has a LOT of scratches and damage to the pcb, including 2 broken controller port traces that I repaired. Still no change though after the repaired traces.

I'm wondering if perhaps the ICs could be the culprit? I'm thankful for any help or ideas anyone has