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: Intake-air system removal/installation
Warning
When the engine and intake-air system are hot, they can badly
burn. Turn off the engine and wait until they are cool before removing the
intake-air system.
Fuel vapor is hazardous. It can easily ignite, causing serious
injury and damage. Always keep sparks and flames away from ...
Mazda 6 Service Manual: Contact Authorized Mazda Dealer and Have Vehicle Inspected
If any of the following warning lights or the indicator light turns on/flashes,
the system may have a malfunction. Contact an Authorized Mazda Dealer to have your
vehicle inspected.
...