You can yes check out each cell by charing it individually and then paring them up however most of the time the fact that you have to unsolder and solder the batteries will sometimes cause more a perfromance loss then trying to re-match them . Also do not mix the 3800's in with the 3300's. Another thing to remember a pack is only as strong as it's weakest cell.
What I would do is check each cell with a volt meter and look for any weak links and replace just those cells rather then a complete re-match.