Do the easy stuff first Hugo. Bleed the clutch fluid. Lubricate the end of the pushrod where it passes through the release arm at the bellhousing.
Then watch the movement of the pushrod as a helper presses the clutch down and up. The action should be smooth. If there's a physical "click" it should show. It might be stiction in the slave cylindr, but a fluid change and lubrication of the pushrod is the best start.
Also check the condition of the clevis pin at the pedal. The pin is soft metal and is known to wear, sometimes drastically.
