Where do we order individual transmission gears?
I only see individual sprockets there. I would recommend the CD Swap system, or get the specs in this Zipped file http://www.ifirobotics.com/docs/FRC-2005-TRAN_KIT_DRAWINGS.zip and then buy similar gears, then alter them yourself. Or just buy another whole transmission kit.
Since this is in the Educational Robotics forum, did you mean for robovation? If so, you can get them here: http://ifirobotics.com/edu-motion.shtml