Actually the only asysmetrical gear in the train is the output gear (that protrudes from the case, for the horn). While all others have a full set of teeth all the way around and all mesh and spin happily, the horn gear has one side cut away to make room for the mech. stop built into the cover, so you have to center that gear to get the cover on. I took the good servo apart, and put it back together with no attention to gear orientation other to obtain mesh, and get the mech. stop to line up enough to fit cover. Worked fine, so took it apart again and used gears from one of the blown servos, worked fine. So I suspect there is something gone by the board with in the motor chamber as I can't find anything amiss in the gear chamber (other than the stripped gears to begin with of course).

Elmo Te