Mazda MX-5 Miata Sport 2007 Manual page 711

2007 Mazda MX-5 Miata Sport
2007 TRANSMISSION Clutch - MX-5 Miata
Fig. 25: Measuring Wear Of Diaphragm Spring Fingers
Courtesy of MAZDA MOTORS CORP.
2. Measure the flatness of the pressure plate with a straight edge and a feeler gauge.
If it exceeds the maximum specification, replace the clutch cover.

Clutch cover maximum clearance
0.5 mm {0.020 in}