Carelessly one day I removed my keyboard cable too quickly from my iMac DV SE Snow, causing the plastic centre piece on the "female" part that guides the filliments together to snap and come out. I thought nothing much of it until I tried to glue this white piece of plastic back in place, the result being that the metal connecting filiments inside my iMac do not correctly line-up with whatever USB device I plug in. Result = 1 less USB port

What can I do? How easily can I replace the USB board/ports?

Any help would be much appreciated.