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: Manually Shifting Up
You can shift gears up by operating the selector lever or the steering shift
switches (some models).
M1 → M2 → M3 → M4 → M5 → M6
Using selector lever
To shift up to a higher gear, tap the selector lever back (+) once.
Using steering shift switch (some models)
To ...
Mazda 6 Service Manual: Cruise control switch inspection
1. Disconnect the negative battery cable.
2. Remove the driver-side air bag module. (See DRIVER-SIDE AIR BAG MODULE
REMOVAL/INSTALLATION.)
3. Disconnect the cruise control switch connector.
4. Inspect for resistance and continuity between the cruise control switch
terminals using an ohmmeter. ...