It is not uncommon for the smarts to suffer from input shaft seal failure.
This can easily be identified by either a mist, or a drop of transmission oil on the bottom of the bell-housing.

Start by removing the gearbox.

You can clearly see the gearbox oil coating the inside of the bell-housing.

You need to unclip the retaining pivot spring from the end of the clutch release arm.
Push the spring clip back through the hole.

You won't be able to remove the arm until you have unclipped the release bearing.
Remove the clutch release bearing by lining up a small notch in the bearing with the key on the input shaft, and pull.
You need to overcome a small spring clip on the back of the release bearing. (Video example here.)

The release arm should come off, but be aware that behind the bearing and release arm, there is the return spring. It's not a strong spring so won't disappear, but you MUST retain this spring.

Now remove the input shaft cover; it is retained by 2x E8 bolts.

Here you can see the seal, and how it was leaking.

Removal of the seal is rather crude, but use a thin screwdriver/spike to lever out the seal.
At the 'bottom' of the seal is a drainage channel (forward thinking!); start here and work around the seal at various points.

Once the seal is removed, take the opportunity to thoroughly clean the inside of the bell-housing. Brake/clutch cleaner works perfectly.

Dry the inside carefully and make sure there is no contamination behind the seal face.

Push in your new seal, tap carefully into place using a blunt object (eg wooden handle of something).

After ensuring the seal is in correctly, refit the input shaft cover using the 2x E8 bolts.

Refit the spring, release arm, and the release bearing.
Squeeze the spring clips together for the end of the release arm, and push up through the hole.

Ensure that the release arm/bearing are all free to move/pivot on the mount, and that the actuator is correctly lined up with the release arm.

Refit your gearbox in the reverse of removal.