Wipers have stopped moving but wiper motor runs. on 1995 Toyota Camry

Wipers will not move but motor seems to be working fine. If I manual move the wipers they will return to the home position but will not move back and forth on their own. What is the problem?

2 answers
or wiper arm nuts are loose under flip up covers
Wiper transmission linkage seperated , need to inspect and replace failed part or assembly.