How to fix sticky keyboard keys

Sometimes my keys work fine, like now. Other times, without rebooting, certain keys like the R, Y, 5, 0, do not work when I press them. Sometimes if I press the R and Y key several times, the R and Y will appear. Other times, repeatedly typing the R and Y still dont get them to appear.

This problem happened, it seems, shortly after I disassembled my laptop. What would cause this problem? I think it may be one of the wiring connectors that connect the keyboard to the main unit, and not an issue with the individual keys. Should I reopen my computer, disassemble the keyboard, and reattach it, which of the 3 internal cables would affect this?

What should I try to fix this? Its very annoying having to use the "On-Screen Keyboard" to type the Y and R keys when they temporarily stop working on the keyboard.