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: Fuel tank inspection
Caution
Disconnecting/connecting the quick release connector without
cleaning it may possibly cause damage to the fuel pipe and quick release
connector. Always clean the quick release connector joint area before
disconnecting/connecting using a cloth or soft brush, and make sure that it ...