If your clutch petal has ever lost pressure and the petal will not dis-engage the clutch, there is a leak. The leak may be air sucking in or fluid leaking out. First check the clutch fluid reserve, if it is low you will need to identify the leak. There should be a puddle of fluid at the leak. If a leaking line is not the culprit it may be the clutch master cylinder. If the clutch master cylinder or slave cylinder is faulty, there may be no loss of fluid. The clutch master cylinder is located on the firewall attached underneath the fluid reserve tank.

Remove the two nuts that retain the clutch master cylinder to the firewall and the line running out of it. When the cylinder is removed you can look at the circlip that holds the master cylinder components inside. Use a circlip tool to compress the circlip and remove it.

With all of the clutch master cylinder components removed they will appear in the order shown.

Looking at the photo above you will see a long black piece made of plastic or steel called a plunger. Below you will also see the clutch cylinder plunger tipped up on one end. There are six holes covered by a plastic washer on the factory plunger on the right. The replacement is a thin washer that will also cover the six holes on the new clutch plunger.

Now just reassemble the parts back in the order that they were removed. Then you will have to use a little pressure to hold the new parts in as you reinstall the circlip. You will need to bleed the air out of the clutch in the same manner that you bleed the brakes on your car. The clutch slave cylinder (located straight behind the passenger wheel on a miata) will have the bleed screw located on it.?