The 45°+ black metal blade cartridge is labeled + on the end.
Older systems may have a 45°+ yellow plastic cartridge.
Push blade cartridge release down to eject the current blade cartridge.
Turn the new cartridge over and reinsert into the head with the blade facing the CMC board and the notch on the back of the cartridge facing the head, until it clicks into place. It can only be inserted one way.
