1. Verify that the joint shaft is not twisted or cracked.
2. Turn the joint shaft by hand and verify that the bearing rotates smoothly and freely.

Drive shaft
Joint shaft removal/installationMazda 6 Service Manual: Location index
INTAKE-AIR SYSTEM
FUEL SYSTEM
Engine Room Side
Fuel tank side
EMISSION SYSTEM
Engine room side
CONTROL SYSTEM
...
Mazda 6 Service Manual: Emergency Locking Mode
When the seat belt is fastened, it will always be in the emergency locking mode. In the emergency locking mode, the belt remains comfortable on the occupant and the retractor will lock in position during a collision.
If the belt is locked and cannot be pulled out, retract the belt once, and then ...