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: Operating Tips for Audio System
WARNING
Always adjust the audio while the vehicle is stopped: Do not adjust
the audio control switches while driving the vehicle. Adjusting the audio while
driving the vehicle is dangerous as it could distract your attention from the vehicle
operation which could lead to a serious accident. E ...
Mazda 6 Service Manual: Dual proportioning valve inspection (without abs)
1. Connect the SSTs to the brake pipes as shown in the figure.
2. Bleed the air from the brake system.
3. Measure the fluid pressure of the master cylinder and the rear brake.
If not within the specification, replace the dual proportioning valve.
Fluid pressure
...