Passenger side power window won't go up.

Hi guys,

I have got a problem with the left rear door power window. It goes down, but it won't come back up when I press the switch.But on the drivers side power window main switchboard board, I can operate the passenger side power window up and down, but I have to press it with a little bit of force. I originally thought it was the passenger side switch, so I bought a new one, but it still did not go up. The damn thing cost me $85 dollars (australian), so it was an expensive excersize. So my question is, How do I fix this problem? do I open up the driver side door trim and have a look at the main power window switchboard. Is there a way I can find out exactly where the problem is? Do I use a meter? Your help is needed, thanks.