on 10-31 Kathryn from Ann Arbor.Get a mechanic to pull the differential drain plug. If lots of metal is found, the spider gears are going out. Ford[Mercury] has an issue with improper hardening of the spider gears. Eventually when
the gears break, the transmission will not work.
If this happens at the slow speeds of reverse, you will probably get away with a rebuild. If the gear breaks at highway speeds , you could destroy the whole transmission, and possibly be
involved in an accident.
Get it check out very soon!
G-M