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: Rocking the Vehicle
WARNING
Do not spin the wheels at more than 56 km/h (35 mph), and do not allow
anyone to stand behind a wheel when pushing the vehicle: When the vehicle
is stuck, spinning the wheels at high speed is dangerous. The spinning tire could
overheat and explode. This could cause serious injuries.
...
Mazda 6 Service Manual: Active Adaptive Shift (AAS)
Active Adaptive Shift (AAS) automatically controls the transaxle shift points
to best suit the road conditions and driver input. This improves driving feel. The
transaxle may switch to AAS mode when driving up and down slopes, cornering, driving
at high elevations, or depressing the accelerato ...