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: Foreword
Outline
There are two on-board diagnostic functions: Operation mode, which
inspects for and indicates correct operation of the input signals to the
control module, and condition detection mode, which indicates troubles in
the system.
The two functions can be done using either of the f ...
Mazda 6 Service Manual: Side air bag sensor removal/installation
Warning
Handling the side air bag sensor improperly can accidentally
deploy the side air bag module, which may seriously injure you. Read AIR BAG
SYSTEM SERVICE WARNINGS before handling the side air bag sensor. (See
SERVICE WARNINGS.)
1. Turn the ignition switch to LOCK position.
2. ...