Thanks for the info, everybody - does anybody know, can a fairly mechanical but non-tranny-expert person swap out the output speed sensor himself, or is this a tranny shop job? A friend has an AW-4 that won't downshift into first but the TPS tests out okay and other diagnostics seem to rule it out anyway. Just leafing quickly through the tranny section of my FSM I didn't see any mention of an output speed sensor or how to replace it.