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: Air bag module and pre-tensioner seat belt deployment procedures
Warning
A live (undeployed) air bag module and pre-tensioner seat belt may
accidentally deploy when it is disposed of and cause serious injury. Do not
dispose of a live (undeployed) air bag module and pre-tensioner seat belt.
If the SSTs (Deployment tool and Adapter harness) are not ava ...
Mazda 6 Service Manual: Rear door speaker removal/installation
1. Disconnect the negative battery cable.
2. Remove the rear door trim.
3. Remove in the order indicated in the table.
4. Install in the reverse order of removal.
Rear Door Speaker Installation Note
Attach the speaker with the wiring harness placed in the groove of the door
unit panel.
...