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: Front seat disassembly/assembly
Warning
Handling the front seat (side air bag) improperly can accidentally
deploy the side air bag, which may seriously injure you. Read AIR BAG SYSTEM
SERVICE WARNINGS before handling the front seat. (See SERVICE WARNINGS.)
1. Disconnect the negative battery cable and wait for more tha ...
Mazda 6 Service Manual: Power window motor inspection
Drivers Side
1. Disconnect the power window motor connector.
2. Apply battery positive voltage to the power window motor terminals E and F
and inspect the operation the power window motor operation.
If not as specified, replace the power window motor.
3. Apply battery positive voltage ...