1. Measure the wear of the diaphragm spring fingers.
Depth
0.6 mm {0.024 in} max.

2. Measure the flatness of the pressure plate with a straight edge and a feeler gauge.
Maximum clearance 0.5 mm {0.020 in}

3. When checking the diaphragm spring fingers, mount a dial indicator on the cylinder block.
4. Rotate the flywheel and check for misaligned diaphragm spring fingers.
Misalignment
0.6 mm {0.024 in} max.

Clutch unit removal/installation
Clutch disc inspectionMazda 6 Service Manual: Engine Exhaust (Carbon monoxide)
WARNING
Do not drive your vehicle if you smell exhaust gas inside the vehicle:
Engine exhaust gas is dangerous. This gas contains carbon monoxide (CO), which is
colorless, odorless, and poisonous. When inhaled, it can cause loss of consciousness
and death. If you smell exhaust gas inside the ...
Mazda 6 Service Manual: Refrigerant pressure switch inspection
1. Install the SST (gas charging set).
2. Disconnect the refrigerant pressure switch connector.
3. Verify the high-pressure side reading of the SST (manifold gauge)
and continuity between the terminals of the refrigerant pressure switch.
If not as specified, replace the refrigerant pressure ...