I can't click right.

I've checked every button. They all work except the right button on the circle of arrow keys. I opened it up and couldn't find anything obviously wrong but I'm not an engineer by any means and would love some help. The keypad looks fine and not worn down. The carbon contact doesn't look worn down, maybe a little dusty. I rubbed it over with an unused toothbrush but it didn't help.

Any ideas?