I too broke one of the ears off the input gear when trying to get it through the second bearing. What worked for me though was this. After getting the gear through the first bearing (which is easy) insert the assembly into the support holder. Then put the second bearing partly on by putting it on at a angle so one of the ears is inside the the inner part of the bearing. Then take a small flat-tip screwdrive and insert it between the bearing and the holder and push on the opposite side of gear thats already partially in the bearing. While pushing on the screwdriver just apply some pressure to the bearing and it pops right on.
Matt