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: Dtc c1955, c1956
Caution
When attaching the tester lead to the DSC HU/CM connector the SST
(49 G066 004) must be used.
Diagnostic procedure
...